imperial stout variant help

Hey all hoping to get a little help/advice for some variants on my imperial stout. I was planning on doing 3 variants; a cocoa variant, a scotch aged variant, and vanilla bourbon variant.

If anyone can offer some advice/tips/suggestions for these that would be amazing. I think i need help especially with a scotch and vanilla bourbon variants (mostly on how long and how much i should age for). Thanks in advance for all the help!