Hey guys, first time grower here and I chose to go with mainlines and though I have been researching for the past 2 months I still am left with many questions, new ones on almost a daily basis haha
Brief summary: Plants grown indoors in a 5x7 space with 8 foot ceiling are about 70 days old in MG soil. They are under a vertically hung 400w MH with a hood. Temps in high 70s and humidity around 50%. They get watered every 3-5 days, with every other watering is a feeding. They are up to 40oz and I weigh the pots to keep track of when to water. They have been fed once a week with FF trio in low doses. I have been giving 4ml p/gal of Big Bloom and started with 2.5ml of Grow Big and worked my way up to 7.5ml p/gal. During flowering they will continue the BB and I will add 7.5ml per week of Tiger Bloom. They are currently in 5 gal pots and their heights are 8-9 inches from soil. I am still training them down to keeps the tops separate but not sure how much space they will need.

Basically I want to make sure Im doing everything right with the little I have to work with and if they are healthy and if there is anything I need to look out for moving forward. I had an issue with fungus gnats that is mostly under control for now but there are a few small holes on some of the leaves.

So my first question would be about my FF feeding schedule. It says to stop GB 1 week before flower then 3 weeks after flower to give 5ml per week for 3 weeks.
Im just wondering what is the purpose of this. I believe its to lower nitrogen levels and also for those 3 weeks raise my P and K to help with flowering but Im not sure.

Which leads to my next question and its about when exactly I should start flowering. The answer I find most is flower when your plant is half the desired height. I dont feel this takes into consideration that, 1- Its a mainline 2-I will be flowering with the same 400w MH light 3-the amount of penetration my particular light can deliver.

Continuing with the light, since it is vertically hung I am unsure of the best position for the plants. Do I still want the plants directly under the light or are they better positioned in a circle around the light with the closest tops at a 45 degree angle to the tip of the bulb? And depending on the answer what would be the correct distance range from the bulb tip to the closest tops? Currently they are in a circle around the bulb with the inner tops about 9 inches from the tip of bulb measured diagonally.

One more about lighting. Is there any specific bulb I can screw into a normal socket I can hang next to the MH that would benefit me during flowering?

I transplanted from 2 gal pots to 5 gal pots this week. Till that point I have been trying to water till 25% or less of runoff, adding more water each week as needed as the plants grew and They currently get 40oz. Moving forward I feel like I should not be watering the 5 gal pots till runoff because water would sit at the bottom of the pot and they would be over watered so I was thinking I should just continue adding couple ounces each water and continue as I was and eventually it would even out till I do have run off again. Idk is my thinking correct here? Any thoughts?

I guess I will leave it at that for now.
Appreciate any feedback.
Thanks guys!