What time of day is it? HEL is dead quiet outside the waves.

It will most definitely be a bus arrival, and the bus will take you to the arrivals hall near gate 20. When you get off the bus and inside the terminal building, immediately take the stairs to the upper floor. Do not go through the automatic revolving doors.

It's a 7 min walk to passport control and then 3–7 min to your gate. If there's a letter attached (like 36B), then you'll be leaving from a bus gate. In that case, they will start boarding early. Otherwise, AY very seldom starts boarding at the time indicated on the BP.