The first time you turn on the compressor for the season, you should....
1) make sure the main power has been on for about 24 hours before you actually start up the unit. This is to let the crankcase heater warm the oil and boil out any refrigerant that has migrated into the compressor.
and / OR
2) wait for a warmer day outside so the compressor is warmer then the inside coils.
Liquid refrigerant will migrate to the coldest part of the system. You DON'T want that to be the compressor when you start it. Liquid doesn't compress very well.