Emirates is 2 hours later than SFO, but SFO does coincide with IAD and SIN. BOS is 30 mins later, but you might run into some UK departures as well:
https://www.cph.dk/flyinformation/af...te=&time=12:00
Currently the app says 0-5 minutes wait for passport control, not sure how accurate that is, but sounds pretty good for this time, if it is!