Magic,
There is no min days off protection with ITU training. They will only drop trips that conflict with your ITU footprint as well as any trips after ITU since you will no longer be assigned to that bid pack. The month you finish ITU training they will honor the number of days off that you bid for that month. So if you finish ITU training in May and were awarded a line with 15 days off, they would build your custom line so that as long as training worked 13 days or less, you would not get any trips that had you working more than 13 days total. ITU training never counts for days off protection.
If you meant that you have recurrent training, then they will drop the shortest trip that they can that gives you 13 days off since the contract only provides for 13 days off in a 4 week month.
Hope that makes sense.