Extenda said it right. Having been through an IQ on the 220 <2 years ago, I can say you will have more than enough quality materials provided to you be Delta. The only real challenge I felt was getting in repetitions on the FMS and other stuff that requires pushing of buttons and set-up. That was the 200 series, accomplished in a Flight Training Device. Know your flows, procedures and memory items, and it will all come together.
Once you have Delta computer access, look up Kevin Freeman in iCrew. He's a 220 F/O who knows the plane inside and out, and publishes the A220 Cheatsheet - he blasts it to subscribers for free, including updates when appropriate. It's a 10 page "hardcard" (if you print the PDF and laminate it) that has lots of condensed memory joggers, useful numbers, flow summaries and cool tips and tricks (who knew that re-booting a single display screen could solve a take-off data upload issue?).
The 220 is a cool machine, but just because it's one of our smaller jets, don't assume it's the promised land for new hires. It is not necessarily junior and the trips are not as good as they could be. The GTF engines and general design profile favor hours in the air, but Delta at times seems to think it's a 717; short turns are all too common, and seem to find their way into otherwise fine trips. I lasted 5 months and bailed due to continuous trip degradation - even at 4% seniority. Look at bid packages/awards and category lists before committing to the fleet.