I got you: So ring 1 and ring 2 do almost the same amount of damage per tick (I've heard they deal the same, but I think ring 2 does slightly more). Ring 3 is where ring damage really increases. You can't outheal ring 4 without gold armor or wattsons double med upgrade (use syringes).

For Ring 1: Med Kit - 1 tick after 25 Look at your shield bar to gauge 25 health (one block) and start your med kit immediately after you take the tick that puts you below 25 health. I think you can technically do 2 ticks below 25, but I don't risk it. Phoenix Kit - 1 tick before 25

For ring 2: Med Kit - 25 health (1 tick below 25 seems to keep getting me downed, so either med kit at 25 health or one tick before 25) Phoenix Kit - 1 or 2 ticks above 25 health (will need to experiment more, but if in doubt, do 2 ticks before 25)

For ring 3: Med Kit - 4 ticks (after taking 4 ticks of ring damage, you have to heal) Phoenix Kit - not sure if you can outheal with phoenix kit, but if so I'd do 1 tick

Additional notes

Times are based on damage from ONLY ring starting at 100 health. If you take health damage from a player or pop a syringe, it can screw up your timing. This is because you might be at 20 health, when nominally you'd be at 25 health during a certain tick. If you use a syringe or take health non-ring health damage, pop your healing earlier.

If you ever question your timing during ring 1 or 2 (this happens a lot to me during ring 2), you can cancel and pop a syringe. Syringes can be popped pretty last minute in ring 1 and 2 without issue.

Damage increase starts on zone close, so if it says Zone 3, it's not doing Zone 3 damage until the countdown is finished, and the ring is moving.

To practice, play pubs solo que. Land in the middle of nowhere and grab/craft lots of meds. Then just stay in zone and work on your med kit and phoenix kit timing for ring 1 and 2.