This Saturday (20/12) we’ve got two trains coming through, both of which are new to the line.

A4 60007 “Sir Nigel Gresley” will be coming through some time after 12:15 heading for Norwich. You can find more details here but it doesn’t include detailed timetables and although it looks like it leaves Cambridge at 12:15 it may well be some time at Coldham’s Lane junction taking on water before it passes Milton (for example Tangmere was there for about half an hour).
It should be returning at around 19:00-19:30.

We have also got a diesel hauled special pulled by D1015 “Western Champion” on the same day. Details here but don’t include many times other than that it will pass Milton somewhere between 09:50 and 20:10 heading north. Liverpool Street to Cambridge is about an hour without stops so it will probably pass Milton some time shortly after 11:00.