Dont know your area, but I know here its not too late for nuc s. Welcome to Beesource and good luck in your endeavor. G
Feed them 1:1 the bees won't have to work as hard to cure the syrup. It's rare that they will quit taking sugar syrup, they'll keep taking it if you keep giving it. The rare time they quit is only momentarily and they'll go right back to taking it. I don't believe it's too late to get started for you just feed like others are saying and keep an eye on them.
Not to hijack - overall the consensus seems to be that the OP has time! But it's so interesting to hear the take on sugar water. Nectar is higher in water content then either a 1:1 or 2:1, is it not? I went about reading a lot of feedback on the 3 common ratios including the 1:2 and most if not all who actively tried to use all 3 ratios found no real difference in it's efficacy in building up comb and brood. In my area it's dry and hot (North of Reno, NV. Hello desert!) so, the 1:2 helps keep bees hydrated and cool, while still supplementing. I think if you have more moisture you can upgrade to a thicker sugar ratio. I might experiment more with the ratios in following years - When I get up to more hives perhaps feed a few hives each ratio and find what works best here!Actually, feeding them 2:1 (sugar to water) will help them cure it faster. If you do get started now, keep a close eye on the queen and her laying behavior. Requeening in the fall when the colony has built up and is fairly strong is ok. But, if you lose a queen mid-summer and it takes a while to kick start the colony, you could find yourself running out of time as the days get shorter.