Your at the start of your grow season..
worst case, they go to flower, realise the nights getting longer and revert back to veg..
when on 24-0 indoors, best time to go outside, first week last month of spring, all strain dependant but majority of plants will continue to veg without slowing down..
I don't think that the plants are all that sensitive. Last year I bought 5 clones from a nursery that had them on 24/0. I brought them home and immediately put them on an 18/6 schedule. Didn't affect them at at. Then a month later, I hardened them off for about a week and during that time adjusted the lights from 18/6 to 15/9, then put them outside to stay. This was about last week of May. They didn't start flowering until early July (except for Blueberry Muffin which started about 6/20 - but even the nursery said this strain sometimes flowers early).
I have a theory (that's not backed by any data whatsoever) - when you put your plants outside for the first time, they are receiving so much more light intensity during the daylight, that longer night periods probably don't matter. Once they are fully acclimated to the outdoors, then a drop in daylight will trigger the flowers. (Just my thoughts, I could be completely wrong).
I think you'll probably be ok with your current seedlings.
When I first did clones beginning of last year this time 24-0 to 11.5 and they flowered off the bat, but when I cloned back in October they started off 24-0 then 18-6 then I slowly introduced longer dark periods till it matched outside then planted outdoors and it grew fine....Also - If you did want to put them outside and you had no choice but to stress them, the do it now and they will just bounce right back in June, anyways. It would totally reveg and probably before the solstice, even. Stressfull? ya, but it would make buds just the same at the end of the summer.
But heading into winter now and I got some clones going so will veg indoors then put outside for my backward summer grow for mr.Bonsai.
My last harvest a week ago, still hanging due to weather but they drying nice and slow...