Getting the wire on my braces tightened...?

I got my braces last month, and I was supposed to have my first wire tightening appointment this week, but they moved it to next week because my dental hygienist is going on maternity leave, and they need a few days to train another hygienist to tighten my braces and change my bands. I'm upset, because I don't want a rookie brace wire tightener. :( How long will my hygienist be away on maternity leave? And does getting the wire tightened hurt? Will they have to put the lip stretcher in again like they did when I got my braces put on? I'm really stressed.