Where's the "Start Timer" button on the at-home covid test?

I just did my first at-home test, an iHealth COVID-19 Antigen Rapid Test.

First, having my usual case of performance anxiety, I read the directions through carefully three times. Then I laid all the pieces out and proceeded.

I was fine* until I got to step 5, Wait 15 minutes: Start the timer by clicking the “Start Timer” button.

The instructions leaflet did not show a picture of the location or even mention on which part of the paraphernalia I should look for this button. There did not seem to be any sort of button involved in any part of this. There was no button, labeled or unlabeled.

I had a handy kitchen timer ready, and I set that for 15 minutes, so it was okay. And the test did come out negative: I really do have a cold ordinaire for the first time in more than two years.

But shouldn’t somebody have spotted this omission and fixed it by now?

You folks in the know: where is the damn button?

———

*That is, apart from the three-hands problem: holding the used swab, ready to dunk, without letting it touch anything, while opening the little bottle with two hands.