at my lat(45)on june 7th,its a 16/8 schedule,sun rises at approx.5:30 am and sets at approx. 9:30 pm,thats 16 hours,has worked well for me for 4 years,i used to get screwed sometimes using 18/6 with photosensitive strains so i just switched to the 16/8,you could even go 16.5/7.5.if you were close to my lat)i wouldnt put them out until they were at least 7 inches high with good roots,i have found over the years that if i put my seeds to germ at that time it takes up to 3 days to germ,and gives me almost 3 weeks veg,they stand up to a lot more when grown up a bit(2-3 weeks from seeds