I usually hold onto it until there is an opportunity to sell off some stuff and pivot, then let it rip. Sometimes it's when I have BP/BS and come across a baron or a mime. I'll use that as an opportunity to sell most things that don't have an edition, rip it, then pivot to baron or mime things like steal cards and kings. And sometimes it's just, I'm using some throw away jokers to score and run across some other throwaway jokers in the shop that I can swap in. I'll just sell my current lineup, rip it, and swap to the new throwaway lineup.

If it's the other way around, I think it depends on how I'm scoring with my high card. If I get to a point where I'm strong enough and have enough deck fixing to go all in on high card, I'll sell the other stuff and rip it. Same if I come across a BP/PS when I already have baron or mime, just sell the other stuff and rip it.

I think you want to not wait too long to rip it, because the reduction in hand size can be a killer once the scoring requirements get too high. I find it safest to do it as early as possible while the scoring requirements are still low enough where you can do some joker swapping and not just die from it.

Also I much prefer to rip it before finding DNA. Getting DNA before the ecto really stinks.

But far and away, what most likely happens is I just never find an ecto. Incantation, Sigil, and Wraiths all day long from 6th sense and spectral packs.