How long would it take until adult teeth start to grown in?

Around six: The adult first molars begin to erupt around six years of age. The next teeth to erupt will be the upper and lower front teeth, which usually starts around 8 years old. Then the posterior teeth begin to erupt between 10 and 12 years. Finally, the wisdom teeth will begin to erupt around 16 to 18 years old.

Usually 6 yrs old: The permanent teeth usually start coming in around 6 years old on average. Some kids are early while some are later.

Varies slightly: There is no set age that the secondary teeth start to erupt, but 5 1/2 is a safe bet that you will see the lower anterior central incisors starting to poke thru. Earlier than that, the child's jaw is a bit small to accommodate adult sized teeth. Many children are a little older, and that is also perfectly normal.