Warsaw is 9 hours ahead of Portland
Best overlap: 8:00 AM to 9:00 AM in Portland is 5:00 PM to 6:00 PM in Warsaw.
Keep meetings inside 8:00 AM to 9:00 AM in Portland — that maps to 5:00 PM to 6:00 PM in Warsaw. Warsaw is 9 hours ahead of Portland, so you only get about 1 hour of overlap a day — worth locking in a standing time like 8:00 AM in Portland (5:00 PM in Warsaw) before it slips.