So for Cape Breton, you should be there on a Monday, Tuesday & Wednesday.
For the Wednesday, forget about jamming. You will have the time of your life at the Normaway Inn. There's a Ceilidh in the Barn which is the best of its kind and is always played by at least one of Cape Breton's finest fiddlers. The dancing is no caller, none needed, the barn will be packed, it's cheap and the music and dancing are entirely authentic. Not just a show for the tourists. Check out the Red Shoe in Mabou for a folk night and The Dory (if I remember right) in Cheticamp for some extremely friendly Acadian music.
The creamery in Port Hawksbury puts on a grand show but I think that's on a Sunday & Sandy McLean, if he ever gets in here, will tell you about the Sunday gatherings in Judique where you will be welcome to join in.
Piper's Pub in Antigonish is not too far from Truro & The Yellow Cello in Baddeck, the centre of Cape Breton, usually has fine entertainment every night. Avoid the Ceilidh in Baddeck. It's for tourists & not very good.
The Keltic Lodge in Ingonish, Cape Breton is a Flagship Hotel $200 - $300 per night with fine dining and quiet lounge entertainment.
Stop at the first convenient Tourist Information Centre as soon as you cross the Canso Causeway for the most up to date information at the time.
Does that get you started?