I did it a little bit, didn't really use oil cause I just did it in the shower. Not sure whether it helped with the stretching BUT I think what it did help with was showing me where I needed to relax the muscles during the pushing phase ITMS. I think that helped, although by the time you're pushing everything is pretty surreal! I had augmented labour with ARM and synto and did not tear at all.
ETA OMG Nae barely a month to go! That is so exciting, I can't wait to see that BA!