I boil the water in a kettle and then put it in the bottom and on the stove with the rest of the apperatus. I've never had it be finnicky since I've started the brew from warm.

The real issue with the Moka is that the metal superstructure gets overheated and it causes the coffee to scorch. I've had that problem my entire life and never cared enough about coffee to go and try figure it out, but after speaking with some of my friends we found that starting from warm was the key to a foolproof Moka.