I started smoking marijuana for the first time and smoke everyday for a month. How long will it take for the THC to leave my system completely?

Thc. It depends upon a few variables, such as potency, dose per day , body fat and weight, metabolism and other factors related to clearance vs storage in fat cells. If use was for 30 continuous days, average ~ 30-45 days clearance to be certain. Sensitivity of the test used and dilution factors in conc. Of urine. Thc is fat soluble and leaches out more slowly than h2o soluble substances.
Weeks to months. Noticeable drug effects should wear off in 2-10 days roughly, but usual drug tests can detect it longer, for about a month. And it can be detected in hair samples for many months. By the way, it sounds unwise to start smoking marijuana for the first time, and then use it daily for a solid month. Although it's safer than many other street drugs, it still has real health risks.
Why? For god's sake why did you even begin? Notice you now have to look over your shoulder for employment testing or other inquisitive folks. Since you've only smoked a month perhaps you can rethink its use and quit. Be smart, not devious. Biological answers given by other docs are absolutely correct, but that isn't the point, is it?