I would think you should hold as they say .. north of MSN on the 360-R using 15 nm legs at your own speed.. meaning you should start your turn at 15 nm on your outbound leg and can use the speed of your liking.
ICAO DOC 8168
1.3.5 Outbound leg length based on a DME distance
If the outbound leg length is based on a DME distance, then the outbound leg terminates as soon as the limiting DME distance is reached.
http://dcaa.slv.dk:8000/icaodocs/Doc%208168/8168_v1.pdf