What is the departure time? You can visit SQ/TG/UA Lounges based on your class of service. UA now stamps your B/Pass, so if you like to visit multiple lounges, plan to go to UA as the last lounge. I believe *A lounge finder lists fairly correct opening hours.
The one and only MS flight 961 that will depart at 22:00 at a future date.
That's very good to know. Could I not have used an electronic boarding pass to skip the stamping?
Thanks for your help!