I wouldn't do it. This is a large purchase and it's eating up a huge portion of your remaining income. You still need money to live your life and go out and ave fun with. On top of that, it's good to wait for ideal conditions to purchase a condo, but with this big a load, you're not going to be making any significant savings. Are you going to have the 20% down that banks want on a mortgage these days?
If things are this tight you cannot "afford" this car. Sure, you can make the monthly payment, but look how much opportunity you have to give up for it. Too much, in my opinion. If I were in the same shoes I'd enjoy that 330i or maybe consider a bump to the 335i, but the M3 is too much of a financial stretch given your current situation and near future goals.