how long to veg??

i am wanting to do a perpetual grow in soda bottles that i can harvest almost every week. i am just wondering how long i should veg if i am wanting to get at least 8 to 10 grams per plant using the lollipop method of growing? also im needing some advice about lightin as well. im lookin at pickin up a small hps lamp im lookin at either two 70 watts so i can lower one since my plants will be at different stages or just one 150 watt and move the plants up what do you guys think would be better also how hard will it be to cool this my cabinet is 24 inches deep and 31 inches wide and 41 inches tall right now i have 5 26 watt cfls two pc exhaust and two passive intakes temps are staying at 70/72

Shit a cabinet that size You will have to start flowering after a week or so.Remember the plant grows 2/3 during the flowering stage. as for the second light? I personally would use the 150w hope your temp stays down though or build a second flower room and rotat your plants through them