Leading Indicator Analysis

Okay..... so I have daily data lined up in column's "A-C" going back 20yrs. I need to figure out how to determine if the daily oil price is a leading indicator of the daily Rig count. I would like to find the optimal lead time. If anyone could help point me in the right direction I'd be much appreciated (please see attached file) I have it set up that in Column A are the dates (oldest to newest) and in column B is the daily rig count and in column C is the daily oil price: