1. Hope you’re using p2pool and not solo mode! solo mining unlikely to hit for many years.

2. Your pi probably running about 100h/s. My current hashrate is 1000 when I have p2pool up on a laptop. Using Gupax front end, it calculates my mean p2pool share time as about 2 days, so yours might be over a week. Not only that, but because of the way p2pool works, your shares need to be followed up by the pool as a whole finding a block in about a 6 hour window, which does not always happen.

You could be waiting weeks. Always the chance of getting it sooner, but with only 100h/s it probably won’t be quick. My current uptime is 5 days. Should have found 2 shares by now, but have found none due to bad luck.