And even if you're arriving before 3pm on Friday, you can simply pay the day parking rate ($2/day) at the station to cover Friday, then have your airport parking start on either Saturday or Monday.

The above works for all days, not just weekends. If you're arriving after 3pm you do not need to pay for that day as fees are only enforced between 4am and 3pm. If you arrive before 3pm, you can pay $2 for the first day.