Run your fingernail across the surface of the dampener where the seal usually rides (you can usually see a ring around the snout of it). If your fingernail does not detect any kind of ridges (well, valley, actually), it's fine. You'll probably see the ring where the seal rides, but if you cannot feel it with your fingernail, it's fine. If there is a slight ridge there, you can usually clean it up with some emory paper. If a couple quick strokes with emory paper doesn't clean things up, you need the sleeve. If there is a deeper ridge which will not clean up quickly with the emory paper, you need the sleeve.
Something to remember about the sleeve is, when you get it, the new seal which goes in the timing cover will be a matched size to the sleeve, so will be a bit bigger than the original one would be. Do not try to use a sleeve with an original seal it will be ruined short order and you'll be pulling it all back apart to do it again.
As a side point. In these applications, the harmonic balancer can be brought in to where you're heating the sleeve. Have it set and ready to go. That will help so the sleeve has a minimal amount of time to cool. Just don't muss up the wife's kitchen, as she'll probably get pissed at you :P