Historical Prices Immediately Following Bitcoin Halving
First halving happened on 2012-11-28, the price was around $12, after the event the prices started to rally and by April 10th, 2013 it reached over $250, after which it crashed to around $60.

Second halving happened on 2016-07-09, the price was around $575, after the event it fluctuated for a couple of months and then we know what happened next.. $20k top and now it is around $3.5k

The third halving will happen approximately on May 25th 2020
Source and countdown: https://www.bitcoinblockhalf.com/

You can check the dates and see how the price acted on this chart:
https://www.tradingview.com/chart/?symbol=BITSTAMP:BTCUSD