Truck Queue/Wait Time

Hello all!
I'm trying to figure out a logic/formula in excel to calculate the hold time of a trailer waiting in the queue to be taken care of. For example, a trailer (Trailer 1) was requested at 8:00pm and was taken at 9:00pm which took 1 hour to unload/load. Meanwhile, another trailer (trailer 5) was requested at 8:33pm and is already taken care at 8:44pm within 10 mins while the trailer 1 is still sitting on the dock. I want to plot a bell-curve of how many of those trailers that are being hold for a longer time while the trailers requested later are taken care first.
I did highlight the line items 2 and 6 in the spreadsheet attached for an example. Could someone help me figure this out? Thanks!

Trailer 1 is in location Y while trailer 5 is in location Q, how can you compare?