How long until i can change my belly button barbell?

ive had it for 3 weeks now, its not infected and its going good. my piercer lady said i can change it after a month and thats in a week so im wondering based on other peoples experience if i should wait longer or listen to the pros. The lady who did it said i can go back to the shop and she would take it out and change it for me free of charge, but the shop is an hour and a half away from my house and im too young to drive. should i do it myself? and also how long should i wait/? and dont be reduiculous, im not waiting 3 to 4 months! thanks!