ide go with the 5-6th node and if you cut when ur branches are smaller u will have more tops ive had 5-6 tops (kholas) on some of the plants ive topped the minimum i usually get is 4 ide go with the promix hp (high porosity) meaning u can feed and water more u might need an extra light ide probly veg em around 6 weeks (seed) 3-4 weeks (clone) and i find gradually reducing ur timer to 12/12 instead of just flipping over tends to stop alot of my stretch in bloom worth a try