If training came is July 10, that puts a skeleton "everything goes perfectly" schedule as follows:
July 10 - end of July: Training camp. This may be a little long, but it allows for 2 work weeks of camp, and then perhaps a week to travel and practice at the hub site.
August - September: Stanley Cup Playoffs. The regular playoffs take two months. If you accelerate every team to play every other day, which is possible when there's only one travel day for one team in the entire calendar, that means you can squeeze in an extra week for the play-ins and round-robins. You also have flexibility in scheduling when you don't have 20,000 fans who have tickets - you can easily move Round 2 to an earlier date if teams finish early, giving an extra day off during a round. Maybe the playoffs start late July, and maybe it ends in early or mid-October.
October - November: Break, free agency, draft, etc. The SCF teams will definitely want some time off. Plus, my guess is that full NHL games in their own stadiums won't be ready by then.
December: Earliest possible start for 2021? Perhaps delay it into at least January. I don't know where we are on vaccines (which, for some, is a sine qua non for returning to arenas), but I kept hearing "takes at least a year" back in March. Their choice boils down to doing a medium-sized December-May season with many (if not all) games played without fans, OR doing a shortened March-June regular season that might have some fans in limited capacity.