It is hard to say when is the right time to change from crib to regular bed. When you do switch her, there will be times that she will get out of bed. When this happens, just put her back in bed. You may have to do this many times before she stays in bed.
I have three kids. The oldest is now 8 years old and she showed interest in sleeping in a bed when she was about 20 months old. My son, who is now 3, didn't really show interest. But, due to needing his crib for the new baby, I moved him to a bed when he was 20 months old without him showing interest in it. My youngest is 16 months old and she is still in her crib. Since I do not plan on having any more children, I will probably wait until she shows interest.
I always kept a twin size bed in their rooms from the time they were born. I never used a changing table for changing their diapers or getting them dressed. I just did it all on the twin bed. I thought it was safer. Anyway, when I did switch the two older ones to the bed, I placed a bed rail on the bed to prevent them from falling out of bed. My 3 year old is still using the bed rail and it will stay there until I am certain that he will not fall out of bed. I also placed a small step stool next to the bed to assist them in getting in and out of bed if they needed to.