After a century ride this weekend (Seagull Century) I am currently at 1996.05 miles, which puts me close to finishing stage 18. So, 13 days left and under 133 miles left to go. Since I'm averaging 125 to 150 per week, I don't see any problems with finishing this challenge.
Hopefully the little "procedure" I have planned at the doctors office tomorrow doesn't keep me off the bike too long. Worst case, I'll just take two days and crank it out.