Can I work one day less in a 3 week notice period?

I've been working at my current job for about 18 months, and have got another job that I've accepted.

I have a 3 week notice period, and am planning to resign tomorrow. They want me to start on Monday, November 23rd which means my last day at my current place should be Friday, the 20th.

That means if I resign tomorrow, it won't be 3 weeks but rather 1 day less than 3 weeks since tomorrow is a Tuesday. Do you think this will cause any problems?

usa jobs
usa jobs resume
usa hotel jobs
usajobs
usa jobs federal government
usa job in ksa
usa jobs
usa jobs login
usa jobs gov
usajobs.gov
www.usajobs.gov
usajobs.com
usajobs
usajobs.gov official