All depends on the size of your space.... An 8 week veg will give u pretty big plants under a 1000w MH. Those plants will stretch another foot or two when u flower. Left untrained you would have some pretty big plants on your hands Not nearly as appealing as it sounds. Which comes back to the size of your space. And air cooled 1000 watt covers about a 4x4 area. That's what I use in my tent which is 4x4x8. My next grow will have 9 plants in there. But they will only veg for a max of 4 weeks. If I let them veg any longer they would out grow my space. Just to give an idea what I'm talking about This is my biggest girl right before she moved into flowering. This is what she looks like 10 days into flowering (the one on the right. She's taking up at least 50% of my room rn) She only vegged for 4 an 1/2 weeks. All comes down to the size of your grow space and your intended training method. 8 week veg and u will have some monsters on your hands Hope this helps