dont have money to fix catalytic converter.. how detrimental is it to wait a month or two to fix?

[TLB]

Does the mechanic know for sure it is the converter? I think a bad downstream O2 sensor can give the same reading on an OBD. As to hurting the car, I think it depends on the failure mode. The "best" case would simply be an increase in emissions from your car. However, since many sensors are involved in today's engines, feedback to ECU could adversely impact overall engine performance and acceleration. If the failure causes restricted exhaust flow, there could be additional problems.

As you can see I think, I don't know...