you can veg as long as u want but remember the plant goes into flower and then grows twice its size, Its better to have medium to small plants cuz u dont have to give the plant as much nuts to get big buds on a smaller plant plus u need a bigger pot and more soil but in ur case it is in a 5 gallon pot so that should be fine. I use hesi bloom and hesi phosphorus plus in the second half of the flower bcuz they work hand in hand and have a ph balancer in them also the hesi product is from holland so whats that tell you. I usually use gallon jugs to water so ill put a cap full of each nut in a gallon of water. I give the plants each a good sip bcuz u gotta think that if ur sharing a gallon amongst plants the plant is not getting enough water therefor not getting as much nutes as needed and i do it this way so i can water at any time with the same amount of nutes and ik im not overdoing it. If your plant is 8 inches then it will be anywhere from 18-30 inches tall by the end. Also if you wanna get large amounts of bud of ur plant u will need atleast a 400w hps if u ask me but id never go below a 600w hps, all that work needs to b backed by really good equipment. If you want more tops u can put screws in ur pots around the outside top and tie a string to the bottom and pull it to 12like a clock and then tie a second string right below wever new growth u have at the top and pull that to 6 like a clock and tie it, u want it tight but not to tight. by doing that it makes the plant start to concentrate on lower growth giving u more tops and also trainging ur plant not to growtall. There is so much to it and anyone can just throw a plnat in a pot and grow garbage. Its not that easy. The method i just tought u as a lst (low stress technique) another way to get tops is to tap the plant this is a high hst (high stress technique) Im sure u know how to top a plant. And u can flower a plant as soon as it grows roots.