..Been a member for 5 years now and visited probably 12 times. I've never reallly had any issues with check-in. I wouldn't worry about not being able to check-in online. Relax. Enjoy. Have a wonderful time.
I personally would not risk it this early in the program.
As someone else posted, online check in is lacking many request categories.
If you have a problem with your online checkin that close to your stay, you may not be able to contact the member in enough time to fix it for you. That would make me very wary of using it if I were renting.