You should be onboard at least 1 hr prior to sailing time but I would not cut it that close.
If you are flying in try to arrive before noon or the day before just in case there are delays someplace.
disembarkation they usually want you out of the cabin by 8 am and off the ship by 9:30 -10am at the latest.
This is all depends on the cruiselines & immigration (if the ship is cleared)
If flying on disembarkation day don't book flights before noon.
Alexandr Pushkin, Carnival-Holiday, HAL-(old)Westerdam, Orient lines-Marco Polo, Royal Olympic-Olympic, NCL-Dream, Dawn-Princess, ACCL-Grande Caribe, Oceania-Insignia (3), Regatta(4) Marina (1) St Lawrence Cruise Lines-Canadian Empress
Scenic River cruise June 11,2012