Peckdrilling with end mill

However, what's the material you are working with. Wood? Plunge it.  Could well be a Very bad idea you can get fire doing this, or cutter burn out.

What I have been told by quite a few people who operate routers for a living is never plunge. unless it's going into a pre drilled hole, I have seen fires on routers twice's, if you have a dust extractor they burn fast, it's not fun ripping one out and chucking it out the door before the building burns down, the wood uselessly smolders on the router so you have time to get to that.

Endmills are not really designed for full diameter plunging. There is insufficient clearance at the center to allow for chip evacuation, and on top of that, your surface footage at the middle is pretty close to zero. I'd strongly encourage helical ramping or drilling a hole for the endmill to plunge into.