can I oh up/down with new just planted seedlings??

Ive just planted 10 NL autos into a soil mix and I need to no can I use oh up or down straight away or do I need to wait a few days or whatever?? Will it harm the seedlings?

start an keep at 6.3

Nice one mate, they are at 6.1-6.3 I guess that will do?

yep that sounds ok. And soil frequently has some buffers in it so your pH shouldn't bounce around much