Here is my 0 experience advice (again, I have no experience)
If you are growing in soil, that should have enough veg nutes for the first 30 days (FFOF does, that seems to be the soil of choice for many learners like myself). So start feeding it bloom nutes at the first sign of flowering (or slightly before, if you know how long it will take to show flowers on average). I don't think any plant, even a ruderalis, would want any nutes for the first 3 weeks or so. After that, start at 1/4 - 1/2 strength bloom nutes and work up as things progress.
Veg nutes = High N, lower P and K
Bloom nutes = low N, High P and more K
Please, someone with experience tell this grower what to do if this is not right.
Good luck! Hope this helps