New to OWS: Minimum speed to avoid embarrassement

Hello, I am a 50 year old female former age group swimmer. I've really enjoyed swim training for my recently complete first half ironman tri and would love to do some 1-2 mile OWS events. If my 1.2 mile OWS time is ~40', will I be totally embarrassed in an event? I define totally embarrassed, as I'm still finishing while the organizers are ready to go home. Finishing in the bottom 1/3 is not a problem for me. This is about a fitness motivator and comraderie--not about winning :) Also, please recommend a good first time event in the midwest. Thanks!