Hey sour, got any pics to share?
From my understanding the only limit to how long you can veg is your container size, as the plant can of course become rootbound and suffer at a certain point if it outgrows the container...If you can keep the plant healthy and had a container large enough to prevent it from being rootbound, then in theory you could veg forever I think...someone with more experience than me will chime in and correct me if this is inaccurate.
No one can give you an exact time frame for when to flip to get a certain yield because there are too many factors ie; strain, nutes, conditions, etc etc...But also from my limited understanding, the longer you veg the bigger yield you can get. As a general rule of thumb (not to an exact science) the plants will double in size from where you ended the vegetative cycle and when you chop it down (assuming you let it fully mature in flowering). Keep that in mind so you don't end up with your plants outgrowing your tent.