Our comfort advice
It is best to try your harness when suspended if you are going to spend time in the belay station to secure your second.
It should allow you to judge the thickness and density of the padding, the width of the webbing on your back. Estimate the compression points at the thighs and especially at the waist, depending on your body shape, as one model may suit you better than another.
Also take the opportunity to check the correct layout of the gear holders in order to facilitate your movements.