I'm not sure of the effect steroids would have. You might get more info on a big Pregnancy/TTC forum where people discuss meds to avoid and which are ok.
If it was me, I'd ask my doctor or pharmacist and see what they say, but to be honest, if it was a sizeable amount of steroids, I'd probably play safe and leave TTC for that month because I'm alsays very cautious about things like that. That's just me though and my being ultra-careful.