Fan leaves turning yellow this early?

My lower fan leaves are starting to yellow and my plant isn't even developing buds yet? The plant has been healthy up until now?. Is this normal or what should I do?

yellowing leaves could mean a few problems, anything from over fertilizing, bad soil, PH problems, check out the help forum

and buds will only develop when you switch from veg to flower

i put my plants to flowering, 2 out of 6 had some fan leaves pretty immediately yellow and fall off near the bottom....no problems and everything else looks good. I am letting them ride on