Short Term Swim Goal

I remember reading this swim plan a few years ago - and I think I may try and do that - swim a mile. Having said that, I only have 3 weeks and 2 swims/week. I figure I did week 3 this week, so my next swim needs to be: 400;200;4x100;4x50. Next week I can do the 600;300;4x100. The week after that I can try the 1000;4x100. My 50 splits were just over 1 minute - but that's without swimming for 2 months - so I should be right around a minute - which makes keeping track real easy. Not sure when I can do the 1200 week or the 1650 - but I'll figure that out later...