As to testing, there are some dojos where a student is told when to test, but I would say that the majority of dojos simply hold tests on a regular schedule and it is up to the student to decide if they will test. There are minimum requirements, usually the number of practice days since the last test, which, once met, allow you to sign up for a test.
There are also a number of people who don't test at all, or quit testing after Shodan. I stopped taking tests after black belt and have been promoted "by recommendation" ever since.
Go and practice at seminars whenever you can. I remember a guy who came to a summer camp where the first class was his FIRST class. People sort of looked after him from then on, making sure he could fall or teaching him the basics. Aikido seems to attract helpful people like that.
I would also recommend that people check out the affiliations of a school (if any) before they start. I always gave new students the phone number for the USAF's office. Like Greg (Hi Greg, we're doing fine) said, you should also check the online services, like, well, this one!
Soon to be Aikido of Norfolk
currently Antarctica Aikikai