Hatch now or later?

Realistically, we may not have another double candy/stardust event for a while until maybe Easter probably. As far as news go, Niantic hasn't announced any sort of event consisting of double candy/stardust. This link is where Niantic announced what this holiday will consist of: https://pokemongo.nianticlabs.com/en/post/holiday2017

I say hatch your 10km eggs asap. If you've already purchased several Starpieces, I suppose you can use one when your eggs are close to hatching to get a significant amount of stardust from your hatches.

Possible on Valentines.

well i'm not sure either.
i got four 10k by now. three of them since the event begun and
as much as i can do with double whatever, i really want some slakoth or ralts with good enough IV to evolve them.

Hatch em in batch and run a starpiece in the back