I can only say that every aircraft both prop or jet that I have been involved with has started inthe order of 3,4,2,1, the reason given mainly to do with hydraulic supplies
The Connie[749] in particular started 3, then 4 to power up the secondary hydraulic system which supplied hyds for the brakes, and amongst other things supplied emergency hyds for the flying controls via the cross over valve so whilst engines 3 and 4 were being started the pilot would check that this valve was open and more important check that the valve had actually closed by the loss of hyd pressure to the flying controls. This check had to be completed before 1 or 2 engines were started as they supplied the Primary hyd system which was used for the flying controls.