veg tent vs flowering tent sizes

Say i want to run a perpetual grow with a 4x8 flowering tent.

How big would my veg tent need to be for about 8 plants? assuming I'm vegging for about 4 weeks.

How many plants are you guys fitting / think is optimal in your 4x8 tents?

Any advice is appreciated.

Also the strain will be northern lights

Im not sure but this is half of my 4x8 tent with 6 BlackBerry fire plants after 5 weeks of veg under a 1000w mh. I have had a few problems so they should be bigger. I hope this helps in some way.