• Movie 14 and Movie 15 •
It's common knowledge that Bulma's birthday is in August. For some reason that information got spread and most (?) accept it. But if we do place Movie 14 in August and assume that Videl got pregnant in the same month, that would put the beginning of Movie 15 in May (assuming Pan was a newborn when we first see her), and thus the battle against Freeza in November.
• Shenlong's Summonings and Universe 6 saga •
From the end of Movie 15 until the beginning of Universe 6 saga, Shenlong was summoned twice. In the first time (off-screen), Shenlong brought the North City back (destroyed by Freeza during the movie events). And the other time was to locate a Super Dragon Ball.
Dende says that one wish takes four months to recharge the Dragon Balls, and so I assume that two wishes takes eight months (I didn't find anything regarding the time it takes when two wishes are made), so if we also consider Shuu's wish in Movie 15, the Dragon Balls would only be able to be used again (i.e to restore the North City) in January, AGE 780. That would put Universe 6 saga in May, AGE 780, as four months passed and the characters would summon Shenlong again to locate a Super Dragon Ball in this saga.
• Future Trunks saga and Universe Survival saga •
The one and only official year we've got so far for Future Trunks saga is "AGE 796" (which if we subtract seventeen from that, we get AGE 779). We would have to push this saga one year ahead (AGE 780 in the present, AGE 797 in the future). Besides that, nothing else is affected. This is the most disconnected saga, changing it brings no major problems.
As for Universe Survival saga, it would take place at least in May, AGE 781, because of the Super Dragon Balls. It was used in Universe 6 saga and it takes one year to recharge. Placing this saga in this year gives a new birth year to Bra but affects Pan's birth year too. The latter is one year older than the former, and she would be born in AGE 780 (we wouldn't have to assume she'd be four-turning-five in the year the 28th tournament happens in this scenario) instead.
• Dragon Ball Super Broly •
Movie 1 would also take place in AGE 781, thus worsening the whole situation. Especially if we take into consideration that "41 years ago" that is shown in the movie.
AGE 781 - 41 = AGE 740. That places the beginning of the movie six years after the actual year it is supposed to be. Now sit back, things are still going to get even worse. There's a five-year timeskip from that until Dragon Ball Minus, thus placing it in AGE 745. Here, Goku was born in AGE 742 and he would be just seven years old by the time he meets Bulma. To fix this, the movie would have to had shown "47 years ago" on-screen (AGE 781 - 47 = AGE 734).
• A way to fix it and conclusion •
Here's how I fix this whole mess:
• Movie 14 - April, AGE 778.
• Movie 15 - January, AGE 779 (beginning) / July, AGE 779 (battle against Freeza).
• Universe 6 saga - August, AGE 779 (I don't consider Shuu's wish as well as summoning Shenlong to locate a Super Dragon Ball).
• Future Trunks saga - Between September and December, AGE 779 (at least one month after the previous saga, to give characters some peace).
• Universe Survival saga - August, AGE 780 (at least exactly one year after Universe 6 saga).
• Movie 1 - September, AGE 780.
• Moro saga - September, AGE 780 (it's possible that Moro saga starts as soon as Goku comes back from Bampa. If it's not the case, then I'd place it in October).
• Granolah saga - Early/mid AGE 781 (it is said that "months" have passed since the previous saga).
Noticed something? Yeah, all of this mess started only because we placed Movie 14 in August, as per an old and outdated information regarding Bulma's birthday. So I ask, do we really need her birthday to be in that month? Some of the Shenlong usages are probably better off if we ignore them too.
We shouldn't really consider every month that is officially stated, as they are there only to complicate things unnecessarily. By ignoring them, we can move the events throughout the year and thus avoiding these nuisances.
You may wonder/have forgotten why Movie 15 takes place in two different months, it's because Piccolo says so. There's a six-month timeskip between the wish made in the beginning of the movie and the fight against Freeza.
If you only follow the manga continuity, then you're in a better situation, since some of the Shenlong summonings didn't happen there (as far as I know, anyway). So you don't need to ignore or make assumptions as the ones who follow the anime must.
I may be wrong about requiring eight months to recharge the Dragon Balls after two wishes. But it's the only logical assumption to make if there isn't any evidence about this. 4 months = one wish. 8 months = two wishes. 12 months/1 year = three wishes (this one is also mentioned in the manga).
If you like this subject, I hope you had a good reading!
