I'm confused by your question... Tell me if I have this correct.
You have a plant in veg, but don't think you need veg nutes, right?
However, you want to know what nutes to use in flower...
Is this correct?
If so, then yea, you really don't need veg nutes if you are vegging for a short time (3-4 weeks). Your soil will have the required nutrients.
As discussed you will need cal/mag if using RO water (I add calmag no matter what I'm doing) and bloom nutes to get you through to harvest. Any bloom nutes will do. I'm sure some are better than others, but common nutes are fox farms, General Hydroponics, Advanced etc..
If you're under LED I think I recall something about plants requiring extra Cal/mag. I can't exactly recall.