Hey, the breakdown for TfL Rail class 315s is somewhat as follows:
I won't post the full list of diagrams as it is too long - your best bet is to simply turn up at a station and wait for a train - it is a short line so it should not be too long until you see one.
Monday to Fridays, out of 20 diagrams:
Only about 10 of these are 315 diagrams now. They're distributed in a way so that the 345s are mostly allocated to the busiest trains during the peak.
In the morning peak, for a 315 your best bet in terms of arrivals at London Liverpool Street would be 0700-0745 and then 0845-0930. Majority of arrivals at those times tend to be class 315s.
A few class 315 diagrams within that time bracket:
0659 Gidea Park to London Liverpool Street
0709 Gidea Park to London Liverpool Street
0702 Shenfield to London Liverpool Street
In the evening peak, for a 315 your best bet in terms of departures would most trains between 1600-1630 and 1730-1830.
Just to name a few 315 diagrams at those times the last time I checked:
1608 London Liverpool Street to Shenfield
1629 London Liverpool Street to Gidea Park
1746 London Liverpool Street to Shenfield
1749 London Liverpool Street to Shenfield
1752 London Liverpool Street to Gidea Park
During the off peak it is a 50:50 mix of both 315s and 345s so one will usually be with you within 20-30 minutes.
Saturday, out of 11 diagrams:
Only 3 of these are 315s - the distribution unfortunately for you isn't the most convenient as two run right behind each other and one is all the way on the other end of the line at any given moment.
Sundays, out of 7 diagrams:
About 3 of these diagrams are class 315 operated. This will change in due course when the 315 duties change in the May timetable.
Refer to the Class 315 Withdrawals thread to see which units are and aren't in service.
