I think the first lot who got the kits would be internal studios and those with strong relationships to Nintendo and those who will be paid to create games for Nintendo, the likes of Platinum.
I see Capcom right up there as they create a lot of games for Nintendo handhelds. Sega for all the Sonic stuff, Platinum for another Bayonetta.
I think the earliest they will release it will be holiday next year. There is no way they will release it before E3 and TGS. This would mean they will be releasing it towards the end of the fourth year of the PS4 and X1 life cycle. Early 2017 will probably be when Sony & MS start giving out their early kits, meaning devs will start to have an understanding of what each manufacturer is doing.