until "two days" before your one year warranty expires. It should state the expiration date of your warranty on your receipt. "Warranty effective through Aug. 21, 2008" and I bought my MB on August 23, 2007. Hope this helps.
It's actually one full year. Looks like you need more math & logic at SF State! Think about it - the exact date one year later would be one full year plus one day - 366 days. Therefore, the day before that date would represent one full year.
All is good, except this year is a leap year, bringing that one day shorter of usual.