HELP! First Grow- Botanicare PBP question DWC

Hello guys! I am growing 4 WW and 1 Sour Diesel x Chronic from seed. It marks 3 weeks today that they germinated and I have chosen to go with the Botanicare PBP starter kit.They are currently on their 4th set of leaves with at least 7 pointed leaves at the top nodes. I have been using only distilled water, and the first set of true leaves at the bottom turned yellow and started to die, along with the second set (3 leaf set). This morning around 4:00am I mixed up 1/4 strength of the suggested dosage on the box and mixed it into some tap water I had let sit out for about 3 days and ph corrected to 5.5. My current ph is @5.7 and temps are 78f ambient and 65f reservoir. My question is how long will it take and what will be the visual signs that I can see to determine that the nutrients are in good proportion? Btw I don't have a ppm meter yet but plan on getting one payday... Just trying to keep the ladies ok in the meantime. Also, is there a formula I can use to calculate ppm by hand so that I can have an estimate of how strong my nutrient solution is (nutes mL/ water mL x 1,000,000 or something like that...)? Thank you for your much needed help in advance!

keep it at 1/4 strength until you get a cheap meter. dwc needs less nutes than other grow methods. ph 5.5-5.7 for veg is great. no real need to leave it out for days, i use tap water and mix nutes in it and straight to res.

if you want a good pbp recipe check my thread, my 3 stages of flower.

Thanks for your advice! I will keep the levels at what they are... My first attempt giving them nutes was at 1/2 strength a couple days ago and it started burning the tips of some older leaves. Since i flushed and went with 1/4 strength there has been no discoloration. I think they may be stunted though, as there has been no growth since then (2 days). Do you know how long this will last? Also, how do you give +Rep?