Forecasting with (linear) Regression - Find best Time Lag of Parameters
I am struggling with a (probably) basic question for a model. I have a forecasting model for sales. I use various independent variables such as sales rep visits, incoming call center calls etc. to predict sales with a linear regression. So far no problem.
Depending on the sales cycle of a business the visit of a sales rep might turn into a sales/revenue one, two or three months later. Now, this is where I am struggling. Basically, I am looking for an algorithm that tells me which time lag (t=-1, t=-2, t=-3 etc.) of a independent variable is best to predict the sales in t=0.
Does anyone have hint for me?