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

[edgarbc1]

my truck service light came on recently
and i brought it into the shop to check it out and do an oil change
they say needs catalytic converter replacement. I didnt have
the money in my auto budget to do this immediately...

how detrimental is it to the vehicle to run a month
or two until i build up enough to pay this expense off?

thanks
E