How long will it take for my bichons hair to grow back?

So it was time to take my 5 month old bichon frise to get groomed and we regularly take her to petsmart but they were booked until july 15 which obviously wasn't going to work for us so we went to petco to try it out for one time. Well they ended up like shaving her way too close to her skin and we are never going there again! But anyways we dont like how they cut it so like i said its cut reaaally short and I was just wondering how long it takes for her to get it back like normal length...