Carpenter was signed on Tuesday after Hopkins suffered a strained right groin in Monday's practice.
"I thought it was a high-level (strain) and he’d be out some time, but it’s not so I think it’s going to be a condition thing," Marrone said. "I think if he was a position player I’d be able to tell you a couple days, but I think because he uses that leg I think it’s just a matter of when he gets out there and starts swinging it and see how he feels."
Hopkins was in uniform for Wednesday's practice but did not participate.
Here is the full Bills' participation report from Wednesday's practice:
DID NOT PRACTICE
CB Stephon Gilmore (wrist)
K Dustin Hopkins (right groin)
OL Doug Legursky (knee)
LIMITED IN PRACTICE
S Jairus Byrd (foot)
FULL PARTICIPATION IN PRACTICE
QB EJ Manuel (knee)