I believe ICAO (that would be the regulating authority) says be at the gate minimum 20 before departure. Considering security queues, though, my advice is to check in online the night before and be at the airport at least 2 hours before departure for a large airport. Small ones you might be able to get away with less, but unless you go through regular and know the setup, I would not chance it. Your airline will give you instructions.
Check in counters normally close for bag drop 1h to 45min before departure here in Europe in my experience. Vast majority of airports also now support digital boarding passes in Europe. My home airport is small so I can work with 1 hr before departure; Brussels was 20min queue at security; Frankfurt we were there 2h30 before departure but at the gate for less.than 10 minutes, queues were that long and slow-moving.
YMMV, check instructions.
Source: I fly lots, mostly in Europe.
For locating the camera with BLE. Needs to see relative location, only possible with location permission. Turn it off after pairing.