Now you wait. This is the hardest part. You can sit across the room, read a magazine, or scroll through very important memes. The wasp will eventually explore the ceiling, bump into the glass, and then find the open gap.
Do not stand right at the window. You are a large, warm mammal, and you smell like food to a wasp that might be looking for a sugar hit. Stay back, breathe slowly, and let instinct do the work.
If the wasp seems stuck at the glass pane, use a piece of stiff paper or a mailer envelope to gently guide it toward the open space. Think of it as redirecting traffic, not fighting a duel.