Insight on Ballast Set up Appreciated

I am going to set up two new rooms for flowering only. Let's call them F2.0 and F2.1. The attached diagram shows how I plan to set things up with 4 tables per room.

*********For the purpose of this post lets assume I have figured out all wall, door, light, table, etc. construction. This post is looking for feedback on electrical/ballast arrangement. Your insight is appreciated. *********

I am planning a two phase development. Phase I consists of the following:
- framing both rooms
- all electrical run for both (including two-20amp circuits in diagram and a few 15amp circuits not shown in diagram)
- purchasing a ballast/timer/relay set up that will run 4 lights in F2.0 12/12 and in the future run lights in F2.0 12 on, while F2.1 is off and then F2.0 off while F2.1 on 12/12 cycle.

cycle would reflect---F2.0 on, F2.0 off, F2.0 on, F2.0 off

Phase II development would include just adding 4 more lights and tables to F2.1 and connecting into the ballast/relay/timer set up already established.

cycle (goal) would be---F2.0 on (F2.1 off), F2.1 on (F2.0 off), etc.

MY GOAL: is to run F2.0 and F2.1 in a flip flop manner where one is off when the other is on on a 12/12 cycle. I would like to do this using only 4 ballasts with 8 lights (4 now and 4 more in a few months).

SO, here is my questions:

1. I have been told I can run a 4-ballast set up from two-20amp circuits. I have gone as far as wiring the room this way so please let me know how this wiring can be leveraged. I can easily add another 20amp or 15amp circuit to the utility hallway between the rooms where the ballast will be powered if necessary. Thoughts?

2. What ballast/relay/timer set up would you suggest. I have been told I can buy a 4-ballast that will run off 110v (two-20amp circuits) and if combined with a relay/timer will swap the ballast power 12/12 between the two rooms. Any insight on what specific equipment and where I can buy it would be appreciated.

3. Any feedback on the set up in general. Keeping in mind rooms are already framed and wired as shown in diagram so I am not excited about taking those parts apart.

Thank you for your support in expanding my op.

BM

most manufacturers recomend that the ballast not be run 24/7, a short cooldown period is needed, I doubt the plants would notice 11 &1/2 hr light cycles giving the ballast 1 hr a day cool off time & your ballasts will thank you.
bear in mind the relay will be switching power after it comes out of the ballast so it will have to be rated for high voltage(over 300 volts).
since your timers will be powering a few relays instead of the ballast,a cheap timer will work but you still need a good timer if you are going to cool the ballast for an hr a day.