Sorting a massive amount of data

Hello,

My boss has asked me to find out how much each sales person has sold in their first 8 weeks, 16 weeks, 24 weeks,40 weeks, 1 year, 2 years and so on to set some new targets

I currently have the spreadsheet (60 thousand lines long) that list every deal with booking date, the persons name and start date but i have no idea how to get it to sort into the specified weeks/years above?

There is about 300 employees :-(

Anybody help in this matter would be much appreciated

Kind Regards