Should I start mass hatching now or wait for the event?

It depends on your style of play. If you walk a lot and run a ton of incubators at all times then start now because you will hatch many batches before the event even starts and You will stock back on eggs before then anyhow. If you prefer to only run a bunch of incubators only on special occasions to save on money then I would wait until the event to start mass hatching. I don't believe there will be double candy from hatches this go around anyhow based on all the info we have. If you have a large stock of tens that could be another potential reason to wait as they have stated the xp bonus will be "huge." That's just my two cents :P

Really, there's no reason to rush to hatch or evolve...It's less than 1 week and doing it when there is no event equals no bonus...

For all we know, hatching eggs could give bonus EXP and according to what was leaked earlier, there was actually mention of extra EXP for hatching eggs.

Bottom line is do things where there is no bonus = non-optimal play...

This does not apply to rich players who run 9 incubators or play with constant lucky eggs anyways.

Im letting my coins build up anyway for a mass incubator purchase.

"Huge XP bonus" will be for nice, great and excellent throws only. There is no particular reason to wait for this event to hatch eggs.

I hope it's actually huge...The last get more candies from egg hatches meant 1-3 candies which was a total letdown not worth mentioning in an event note.