Vacuum at least once a week.

Carpets should be professionally cleaned every 12 months.

If you have children and  / or pets, carpets should be cleaned every 6 months or as often as you need.

Your carpets are your investment you should have them protected with carpet protectant every time you get them professionally cleaned. Carpets that were treated with protectant when purchased should have protectant reapplied after cleaning.