Kindling and trinket use

[Xeno]

If using Kindling and have a trinket with a cool-down such as Tarnished Sentinel Medallion, do you use trinket on cool-down or wait to use until combustion and trinket line up together

[Devlonir]

General rule of thumb: Save trinket for Combustion.

[Xinder]

You use the trinket on cooldown. When using Kindling it's never good to delay combustion. The whole point of Kindling is to get as many combustions off in a fight as possible so delaying it to wait for Owl trinket is counter productive. After the first combustion/trinket are used then you just use the trinket as it comes off CD. You could certainly save it if you needed some extra dps for a burst add window or something like that, but otherwise just use it on CD.

[talisin]

It comes down to fight length, spec, initial dps and boss fight.

The owl benefit from the crit rating. Also, you do more casts within a combustion window and therefor you have a higher chance of the second attack from the owl which is based on the amount of casts on the target,

You should not delay combustion but you can delay the owl IF the fight length does not exceed a loss in one additional owl cast.

With kindling you will have combustion every ±1.30 min of the fight. If you add an average of 30 sec for the first 10% of the fight before you combust and you use Owl with the first combustion your Owl timing would be something like this:
1: 30sec
2: 2:30min
3: 4:30min
4: 6:30min
5: 8:30min
6: 10:30min

Your combustion timing would be something like this:
1: 30sec
2: 2:00min
3: 3:30min
4: 5:00min
5: 6:30min
6: 8:00min
7: 9:30min
8: 11:00min

As you can see you can delay your owl for different fight length without loosing 1 additional cast.
You can do the math by yourself also you can consider if using the owl on pull with firestarter would be more beneficial. Again, to min max you need to know the fight length, the length of the first 10% and any other things like hero / lust or haste buffs or damage buffs.

Hope this makes sense?