question on lighting

I got a 5x5x7 grow tent and will be doing my veg under 6 t5 fluorescent tubes 3x cool white and 3x warm. White then I will switch my system out to a 600watt hps light but I was asking will the 600watt hps been enough for 4 cannabis plants

It should be enough. Are the plants bushy? If they are you need to trim the little sap suckers from the lowest part on plant up to the canopy. Trim the off everything that's not getting enough light as your tops will fatten up greatly. Besides u can use the t5 as side lighting. That's gonna help out for sure.