Theres automation software out there to do it if you have thermocouples, but if not, a simple excel sheet could easily draw you an accurate graph by way of manual entry. Create a spreadsheet with the first column being time, intervals of .30 sec for say 20 mins and the row adjacent will be the recorded temp at said interval so it's look like |6:30|170F|. Record data every 30 seconds. Your first reading would be your drop temp, last reading would be dump temp. Along the way note down where 1st crack, second crack, air-flow changes, etc. happen and highlight the cells accordingly.
When you're done, highlight all of the cells, and have excel draw a graph based on the data for you. Thats how I would do it.