Light green/yellow/brown leaf and slow veg growth issue w/ pics!!!

(Background Info)
1. Started from seed in root riot cubes on 8/24
2. transplanted to solo cups with Light warrior soil on 9/1, have been watering with distilled water every other day or 2 with minimal run off. I have not fed Nutes yet.
3. Indoor 18/6 light cylce under 900watt full spectrum LED. TEMPS NIGHT/DAY: 77-85 RH NIGHT/DAY: 60/50

(Plant Issue)
1. Bottom leaves are turning light green/yellow/brown. Starting from the tips/edges of the leaves going up to the stem
2. Some plants have extreme growth stunts, leaves turning dark brown but not crispy burnt.
3. Both issues started about 4 days ago. I have multiple strains in the same environment but only a few are having these issues.

(Theories)
(Watering with too high ph)- I have seen online the soil Light warrior has tested at 8.5 ph. I haven't checked the ph of my exact bag of soil or the ph of my distilled water, which I have researched to be anywhere from 7-8ph. Should I adjust ph lower when watering like 6.5?

(Nutrient deficiency)- I have not added any nutes and was told Light warrior shouldn't need any for 4-6 weeks. I am approaching the 4 week mark so should I start a feeding schedule?

My plan was to measure the ph of my distilled water, and ph run off of soil to make sure it wasn't high like 7-8. Also measure the EC/PPM of the soil run off to see if I should start adding nutes. Appreciate any help

Those bottom baby leaves will fall off and die; totally normal. Light warrior has basically nothing in it; it’s just a very well draining medium to pop seeds in. Maybe too well draining. Transplanting from the root riot cubes or whatever may have dried out the tap roots. Next time pop seed directly into your light or spent soil with a little worm castings added. Those burnt leaves look to me like heat and/or lack of moisture problems. Cannot be ph lockout because there’s not much in that mix to be locked out of. They don’t look that bad to be honest; they will recover w/TLC. A few of these are still feeding on their seed pods; you sure they were all started at the same time?
Make sure your lights are pulled up high enough to prevent burn; cheapo leds can burn tender young leaves if they are too close. Keep the soil moist but never saturated. Use a hand pump mister to keep the root zone nice and moist as they develop. I know peeps are like dont overwater them but it’s still vastly better than underwatering at this point. Give them the love when they need it. When they get a little bigger & roots reach the bottom of the cup put them in a tray or something and water from the bottom passively. Don’t even bother to check ph or ppm runoff; measuring stuff is just gonna have chasing your tail.
Before you go dumping a bunch of nutes on them that they don’t really need yet here’s what I suggest you do: go get yourself a bag of decent organic soil and a bag of worm castings. Get also some granular mycorrhizae. Put a little worm casting as a top dress on your cups around the stems. It won’t burn or hurt them in any way. It will help retain more moisture and add microbial activity to your currently stark soil which will help your plants become healthy green and strong. Give them another week or two to recover. You’ll notice a difference by then I think.
Then get a big old tote bin or similar vessel and dump in the organic soil mix. Add 1/3 worm castings to this. If that makes it very mucky add in some perlite and/or coco coir. Transplant to this mix and sprinkle some mycorrhizae in the hole so it touches the root ball when you do. That’s it. Will you need nutrients later on when they get bigger? Probably. You’ll definitely need cal/mag as you are using distilled but I would hold back on giving them anything for a few more weeks. In a good soil they won’t need much until they’ve been in the same pot for awhile. Try to find something like ocean forest or or Kellogg’s or equivalent.