veg to flowering questions

i am 5 weeks into my first grow and in about 2 or 3 weeks i will be going into flowering. right now i am using dyna grow and when i go to flowering i will be using dyna bloom. my question is when i go into flowering do i need just to empty my res and when i fill it up just do not put any dyna grow in there and just use the dyna bloom? or do i need to still use the dyna grow along with the dyna bloom? and how tall should i let the plants get before i go into the flowering?

Let your plants get about 2 feet. How many plants do you have. And when you switch your lights over to 12/12 then change your nute rez that same day and put the bloom in.

ok, right now i have 6 plants and i hope some of them are female. it may be a little longer than 2 weeks if i should wait untill they get 2 feet because they are about 8 inches right now. i see you said to change the rez that same day an then add the bloom so when i do so i should not put any grow in there right?