A good suggestion was made in another thread about buying a plane to get your ratings.
I am a fan of this method, and was wondering what others thought. I sort of did this myself as I bought a plane at about 25 hours into the process.
One problem with this is that in addition to learning to fly, you get to learn to be an owner. It takes extra time. The other problem is that you can’t just take the other plane when yours is broken (assuming you either have a different model, or just couldn’t bear the pain of renting a plane when you already own one).
I put my plane on lease back, but don’t necessarily recomend this for everyone.
Here is the deal. Once you are soloing, you can practice a lot more, but when you get close to the finish you don’t save time because you become instructor dependent again.
I recommend you finish your ground and solo before buying. Finish the ground so it is not a third draw on your time. Solo so that you can get an idea what a plane is supposed to feel like before you buy one.
Lastly, unless you are sure a 4 seat trainer will be the plane you want to stay with, look into a 150 or 140 with low engine time to save money on fuel and capital, or a DA20 if capital is less an issue.