If you’re a Virginia voter, the registrar must receive your application by 5pm Tuesday if you want your absentee ballot mailed to you. Arlington’s registrar accepted my application by fax, so that’s a quick option for those with access to a fax machine.
After that, if you find out that you’re going to be busy all day on election day, you can vote in person until Saturday before election day. For Arlington the early voting location is open until 5pm on Saturday.
Remember, the absentee voting rules are very lax; common valid excuses include “I’m going to the next county over for a walk”, “I work in DC”, “I go to school outside the county”. Also, if you only care to vote for President/Vice President, you don’t have to have an excuse at all (If you live in Arlington, how hard can it be to arrange to be across the border at some point during the day?). Don’t get stuck in a long line on November 4th. Get it done early.