The way i work usually is that i open the OMF in a new session based on the template in pro tools. I separate and clean the OMF like sending all you sfx to your template sfx tracks or taking two mono tracks of the same thing and putting them on a stereo track etc... Afterwards i delete all unused tracks and i do a "save copy in" and rename the project OMF_Name_DDMMYY. Then if i have to send it to a Engineer in another studio he can just to import session data of the OMF.ptx and import in his own workflow.

So you open a pre built template first and then import the omf. That's the way I would do it but I have seen a few on line tutorials open the omf first and then import the template. I was just wondering is there any advantage in doing it that way.

There is no difference between both, it's just a way of working. I do both.

I don't think it really matters what you do first... I have done it both ways and it worked fine.