If you have a classic friendly tester he will probably allow adjustment there and then (if you heve removed the trims!).
I like to do it in private, and this has always worked for me.
Measure from the floor to the centre of your headlamps. (Hopefully both the same).
Measure the distance between your headlamps.
Put your car a couple of metres from a wall or garage door, on the level.
Find the centre line of your car, follow it forward and mark it on the wall, with masking tape if necessary.
Measure out left and right from the centreline half the headlamp spacing each way.
Follow that measurement up the wall vertically with a plumb line or spirit level, marking the height of the headlamp at each side.
You now have a mark on the wall corresponding to the centre of each headlamp.
Your headlamp aim should be just below the mark, and the hotspot/kick-up should be to the left of the mark. It can be well left of the mark, as long as it still lands on the headlamp test rig. See https://mattersoftesting.blog.gov.uk/th ... s-changing
If you want to be accurate, you can calculate the percentage drop from the car to the wall, but there is quite a bit of leeway, more so recently. At two metres, it needs to be about 1 to 2 inches below the mark. (Forgive mixed units of measurement).