Small aircraft pilot reported crossing below an approach fix altitude during approach. ATC notified the pilot and flight continued to land.

Narrative

We were being vectored initially for the ILS 22 at AVP. Because of this; we had activated vectors-to-final in the Garmin G1000 in anticipation of intercepting the final approach course outside of the FAF; WEXIN. The system was receiving the correct localizer frequency and the needle was showing the inbound course of 222 degrees. At this point the controller told us to 'proceed direct COSBY; intercept the localizer; cleared ILS runway 22 approach.' I had been used to receiving vectors until intercepting the final approach course; and when they gave us direct COSBY; I was thrown off a bit. We scrambled to find it in the flight plan; and once we did activated a course direct to it. When I did so; the GPS was indicated we should cross COSBY at 2800' MSL (or at least that's what I thought I saw); so we began descending. After intercepting the final approach course; the controller told us to contact tower; but also questioned my altitude. I said that the minimum altitude at COSBY was 2800' and he responded in the negative; that I should have been higher. Thankfully; the weather was VMC so I could see the terrain. But the lesson learned was that I should have cross-referenced the approach plate to verify the minimum altitude at COSBY. Had I done so; I would have crossed it at 4000' and descended safely after crossing.