Unless you're doing some intense video editing or 3D modeling, I wouldn't worry about the latest and greatest. For perspective I'm using my 2011 (top tier) MBP as my professional workhorse for design. I put an SSD in it last year and it was like a new computer.
If you can wait, then no biggie, wait til your hearts content. If you need something to do work then got get a computer, anything, it doesn't matter. If you want the latest and greatest and still need to do work, go shop Apple Refurbished for something that is a little cheaper but still has good resell value. When the new one comes out, you can sell your old one.