If I'm wrong someone correct me but the younger a seedling is the closer they want the ph to 7 and the ph they prefer drops steadily toward 5.8 to 6.2 as they get bigger so if they are still very tiny I'd try to keep it above 5 for sure

If you are using those pool testers you'd want it to just look as yellow as possible and you should be fine till you get the tester in especially if they started growing in the first place it's obviously good enough to work so don't kill them...especially if this is your first grow you will have more mistakes that ya might as well get outta the way...from experirence working through an entire grow is more valuable than junking them even if the mj isnt' the most potent it should still be just as good as you can buy anywhere cause it's fresh...that and it's something to look forward to

Anyone have experience for what stages of growth the seedlings start to like the ph dropped?