In the state of Michigan, if a bench warrant is issued for possession of 28 grams or less of Marijuana, what it the time limit for that statute to expire for the warrant?

There is no statute of limitations on warrants.

Statue of Limitations applies to the amount of time that legal action must be initiated. If a bench warrant was issued that means the person was arrested and charged. Therefore legal action was initiated. So SOL doesn't apply. A warrant never expires until executed.

...If a bench warrant was issued that means the person was arrested and charged. ...

Actually, it means that the suspect was charged and is to be arrested. But correct, the warrant doesn't expire and a SOL would be inapplicable.

Not necessarily. A bench warrant can also be issued for failure to appear after a person has been arrested and a trial scheduled.