How do "You" deal with timed abilities.

[FaileExperiment]

I enthusiastically support a QOL change to prevent casts from being interrupted by a buff timer running out mid-cast.

[SieyaM]

You do want to use Impact when its up, but usually I save it for an instance where I dont have a stone or fire available. So I may go Verfire to Aero, then Stone to thunder, but fire didnt proc, so then its Impact to thunder and if my black mana is getting to high, like more than a 15 point lead, then I can do a stone to Aero and even them up. I am probably not maxing out my dps this way or I am making it more complicated then it needs to be, but I usually don't end up with a gross imbalance around my melee combo time and from the 24 man parses I got, my dps is pretty well.

[Vrankyl]

RDM Impact is one of the unique processes you have compete control over, you decide when you want it to be active and can even reset the timer for it just by using Jolt II again. Saying that, Impact has a very generous timer to begin with so there isn't really any reason to keep hold of it, just use it when it's up because there are no real downsides to it, aside from that be sure to balance your mana correctly though.

There are plenty of times where your proc timer may get low. Phase changes, or a lucky string of Verstone and Verfire procs since Verstone/Verfire > Impact for building your gauge will often cause you to start running low on your Impact timer. With how it's coded now it's best to try and weave it in if you can, but they really should change it to where it doesn't interrupt the cast at all by the proc falling off. Even more so since the game smoothly goes into a hard cast of the Verthunder/Veraero if you got through most of the cast to queue the next ability up. To be honest I just don't think it was something they even thought of when designing the procs.

[Rongway]

You do want to use Impact when its up, but usually I save it for an instance where I dont have a stone or fire available.

Mostly this. The thing about Impact is

If you have Impactful, Verstone Ready, and Verfire Ready
and Impactful is about to fall off

Even if you have both Verfastspells Ready, t's a damage loss to cast Verstone or Verfire. If Impactful falls off, you have two procs left. If neither of those leads to another proc, you only got two procs. However, if you cast Impact, you will still have the two Verfastspell procs, so you'll get to cast three. It's the difference between

Verstone->Veraero, Verfire->Verthunder, Jolt II->Verslowspell
and
Impact->Verslowspell, Verfire->Verthunder, Verstone->Veraero

You want to do everything you can to avoid casting Jolt ever. This includes prioritizing Impact over a Verfastspell when the timer is at 8s or less.

[Burningskull]

How would it impact... pun unintended.... RDM if Impact was OGCD and was on a timer like Flechette but could only be triggered by casting Jolt or Jolt 2.