Just a warning though
OK....so It "might" work out if it actually gets postmarked the 18th. But you don't know yet if will be postmarked the 18th unless you mailed it early in the day, or got it in as Certified or Registered mail at the PO service counter. Things put in the box after the last mail pickup for that day may not get the 18th postmark.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
