My recommendation is to start with 5-10 minutes.

Of course, you can decide to meditate for more, but I would recommend you to start small.

Meditating for ten minutes five days a week is much more powerful than one hour twice a month. Think of meditation as strength training (for your brain). A few push-ups daily will yield more results than lifting a heavy dumbbell a single time – in the beginning, five or ten “push-ups” will be your max.