How long do you think Bulma took to build the time machine?

[TobyS]

The time machine is fueled up in 783, I assume completed around then too because she remarks on how she could have made a better one with her old lab, which is the kind of thing you'd say after making a vehicle or something not when you gas it up.

It also wouldn't make sense not to prepare the fueling with finishing the machine, you could send trunks out for fuel while you finish the machine.

But I'm wondering when she started working on it?

Possible start times include:

Right after The androids kill everyone in 767

If the dragon team were training in the afterlife for a rematch then whatever year Baba died ???

When Gohan died in 780, Trunks and Gohan don't mention the machine in 780 but it's plausible they wouldn't. Gohan doesn't factor it in when making his sacrifice.

When Gokus heart medicine was invented. I imagine this could be before 767 but I doubt it. I can't imagine it being too long after 767 though before infrastructure and R&D stopped.

----

Bulma never tested the machine due to fueling time and resources, but presumably the math and programming would be the longer part.

My second question would be do you think she could plausibly make another between 788 when trunks died to cell and 793 when Dabra attacked.
While the androids and Cell are out the way, Trunks states it still took them close to a year to fuel the trip one way in the machine during Blacks reign, which is longer after the peace time, meaning those specilist high tech resources were still dwindling even if the planet had been recovering. But its unclear what resources are used to fuel it versus make it. The theory and math was already done.

How long did it take her the first time and how long do you think it'd take a second time?

[coola]

Trunks anime special showed she probably start work around time

Spoiler:

Gohan was disarmed

kinda shame she didn't tell him she works on it, maybe it would prevent his death?

[TobyS]

Trunks anime special showed she probably start work around time

Spoiler:

Gohan was disarmed

kinda shame she didn't tell him she works on it, maybe it would prevent his death?

That's possible an armless Gohan could also have been the straw that broke the camels back, not just his death.
Also whenever gokus meds were invented might not be the same date Bulma discovered it, I could see her raiding a ruined hospital and seeing it and then thinking about how it'd be nice if she could get it to Goku and then coming up with the idea.


Another interesting variable is that present Bulma doesn't start developing Blue 15 Electro fluid until 779 1 year before "Trunks the Story" in 780, and 12 years after 767 where the Dragon Team would die.
While she might have motivation to work on it earlier she also has less resources.

It could be it wasn't till this fuel was invented she had a fuel source powerful enough for a time machine, she may have brought the time machine out of mothballs after making it we don't know.

The whole premise of this post is that Shin and Beerus aren't dead in any timeline other than Future Trunks,

There's only 5 timelines at the start of Super and Black says "finally I've found a timeline where the meddlesome God of Destruction doesn't exist" There's only 5 total so finally only really fits if he's searched 3 or 4 of them already. And assuming the rings are in creation order it's the most recent one at that point so the one he would go to last.

So I started to wonder how would Shin live. I came up with 4 scenarios broadly:

1/2. He revives the Dragon team with the Namekian DBS perhaps after looking on earth for Goku if he doesn't already know of the guys on Kaios planet in this elongated time frame. Perhaps he meets Bulma there who gives him the scoop and he goes to Kaios world or goes to Kaiosama to ask about the missing saiyan from earth as it's in his quadrant, either way he stumbles into the gang.
This requires the Dragon Team, probably sans an evil and uncooperative Vegeta remain on Kaios and train, which I think they would have gone there initially before Baba died preventing a 1 day rematch. I think Gohan and Trunks would join them there and they wouldn't choose to reincarnate till they know what happens to Bulma and the others for closure.

3. Alternatively Bulma completes a new time machine and goes back to the Unseen Timeline and gets Goku to come and get them a Dende or takes their Dende who they don't need if Kami didn't fuse.

4. Shin runs into Bulma she explains the time machine plan and he goes to new Namek to use their Dragonballs, or uses the time ring to check on the Cell situation and gets backup from there.

5. Shin recruits Broly, I actually think this is less likely only really Whis is implied to indirectly know about him.

[Saiya6Cit]

I support the idea that it was once Gohan lost his arm. It is understood that way in my opinion because Trunks trains during that time lapse because since time traveling was too risky due to Bulma being unable to test it, he really really tries his best to become stronger and defeat the androids himself, and when he could not, he then decided to go along with Bulma's plan. So, if Trunks was 13 when Gohan dies and he travels when he is 17, simple math suggests it took Bulma 4 years to get the time machine up and running.

But I don´t rule out the possibility that she got the idea the very moment the Z warriors all died, and probably even made some schematics of it.