How long after taking antibiotics can you get c.Diff?

Often within 60 days. Most cases of c.Diff colitis occur within 2 weeks of taking antibiotics. Almost all (90%) of cases of c.Diff colitis occur within 60 days of taking antibiotics. However, a few cases may occur up to 3 months or longer after antibiotics. Other risk factors for developing c. Diff colitis include: age >65; hospitalization, chemotherapy, GI surgery & procedures, HIV & use of proton pump inhibitors.
2-3 months. Can happen after any antibiotic, some more than others; can happen after short-term use. Moral of story: if you don't need them, don't take them. If you do need them take them. Probiotics maybe decrease risk.