Implanon running out

My implanon is due to run out in April 2011. We've basically decided that we are not going to TTC when it finishes and with our current lifestyle we really really don't want another child right now, if ever.

So, I wondered, what are the chances that my implanon will run out before April and I could accidentally get pregnant? Should I get this one removed a couple of months
early and a new one put in or should I wait until April to get a new one put in?

When I had my implanons in they both were effective for the entire 3 year period... I didn't even have any break through bleed or similar when it was changed over.

Thanks. DH suggested yesterday that maybe I should go on the pill when the implanon finishes, just so I get regular periods again.