IMHO 'spring' is not the only answer to potting on cuttings.
First need to make sure they have actually rooted. Most cuttings will put on new leaves and growth using stored energy in the stems, even when they have no roots. If roots do grow everything will be fine but if no roots they will soon die. That's just how life is with cuttings.
I wait until I can see roots at the bottom of the container before congratulating myself on successful cuttings.
As soon as I know they have decent roots I pot cuttings into individual pots. Does not matter what time of year that is. Rooted cuttings easily cope with with transplant any time provided you care for them properly - plenty of water, shade from really strong sun for a week or so.