Are you on UA #9903? If so, today's flight arrived at gate B57, 20 minutes early. (That may be a spot on the tarmac since the map shows that Terminal B only has gates up to 52.) They will put you in a bus to take you to the Main terminal for Immigration and Customs. You pick up your bags after clearing Immigration. Even with long lines at Immigration, you will probably have to wait for bags to arrive. You can recheck your bags immediately after clearing Customs. Then you have to walk out into crowds of people and find your way the the purple "Transfer" signs to go through security again. I'm guessing that Immigration/Customs may take 1/2 hour, going through security will take 15-20 minutes. Then you will get on another bus to go to Terminal C or D for United/Ted flights.