Yellow leaf

Your plant looks fine, small funny looking parts on the leaves are quite normal, especially on the first few sets of leaves, as the plant at this age/size is mainly concentrating on developing a decent root system to "anchor" it and to set up a functioning "food gathering system". Once your pant gets established with a decent root system, lush healthy leaves will follow. At this stage, there is nothing to be concerned over. Also, if you are keen on maximum plant health, going to 18/6 will be far more beneficial for your plants. Plants do actually need to "sleep" and leaving them under continuous lighting for weeks or months will severely stress them, as no plant has ever evolved to function under non stop (day)light. Your plant will grow just as fast, if not faster, with a proper day and night rhythm. Besides, cannabis can only grow so much during any 24 hour period, and growth tops out at about 18 hours, meaning running your lights any longer than 18 hours is basically a waste of electricity. The 18 light / 6 dark schedule is not a random number, but scientific fact derived at through 80+ years of scientific experiments into cannabis production. Without "sleep" your plants will not be able to undertake certain metabolic processes that it can not do during lights on time, possibly leading to plants/flowers with incomplete cannabinoids. 24 hour light might be adequate if you are interested in growing "product" and do not care about the end result, but if you are after fine, tasty, quality home grown buds, giving your plants a chance to sleep and live a normal life with light and dark cycles, then 18/6 is your best option for harvesting prime flowers. Hope this helps,......... Organoman.