I would say for the macbook pro 13, now is definitely the right time to buy. The latest version was just released with some noted improvements and broadwell processors. It is likely that the 13 won't see another update for quite some time. If you wish, you could even purchase last generations 13" with upgrade specs and find yourself a really good deal.
Having said that, if some of those specs are important to you, it sounds like you may want to consider a 15 MBPr. They offer far better processing speeds than the 13, a lot in part to the quad core processor, and a lot of those features of 16GB ram and large SSD come in standard configurations, meaning you may spend an arm and a leg trying to max out a 13 macbook whereas for close to the same price you can get a laptop with more screen real estate and almost double the processing power.
If you do look into the 15 macbook, some are saying hold off as a refresh is imminent and I am somewhat inclined to agree. It certainly will be a few months at least before we see a refresh to the 15" line, but it is definitely much less than a year away as well.
On to the imac, it depends on what your looking for I think. If the retina imac is something that you've been looking into, personally I would wait. While I have read that the performance of the current model is totally acceptable, I would imagine that better desktop class components will come in the next version that have the ability to not only effectively drive the display (a big feat in its own right), but also be a true powerhouse at processing and graphics intensive tasks. That seems to be the only concern of buyers of the current gen is that because of the intensive nature of driving such a display, there are some tradeoffs in performance.
I am sure tho that if you decide to go with a non retina imac that you could either find a really good deal or be adequately served with the current non retina version.
Chime in when you decide what to do and let everyone know.
Cheers!
