It's not uncommon for parents to want to meet with sitters before they leave their kids with them. In those cases, we suggest putting out a request for one hour when you'll be home. In the 'Special Instructions' of the request on the first Booking scree, let the sitters know that you would like to schedule a meet and greet. Often times parents will do this with a handful of sitters and then add them to their favorites so they can easily request them in the future. 
You can also submit a request for a specific date in the future when you will need a sitter and in the 'Special Instructions' box you can request that sitter be available for a meet and greet in the evening/weekend leading up to the sit.  Once you confirm a sitter you can call or message her through the app to arrange a time to meet.  If you speak or meet and decide she is not a good fit you can cancel the reservation and submit a new request.  

After you complete your first sit through the app you will be able to message with Sitters who have accepted your request before confirming/booking a sitter.