flowering/vegging

i am currently using 6 40watt flourscent tubes putting off 3400 lumens each i just planted my sprouted seed today how long should i veg for before i try to start flowering or will the plant show me signs its ready to flower

it will begin alternating nodes and show preflowers, takes 3-5 weeks vegging, sometimes a little bit longer. what kind of lighting are you going to use for flower?