Did I miss my opportunity to do a D-rest

I'm doing my first lager; Octoberfest using WL German Larger Yeast. My starting gravity was 1.50 and I pitched a 2L starter. My expected final gravity is 1.014. It's been in the primary for 1 week at 50-55 degrees and slowly bubbling away all week. I took my first gravity reading today and it was 1.18.

My plan was to keep it in the primary for 10-14 days (depending on the hyrdo readings), then do and D-rest by bringing it up to 65-68 over 2 days, letting it rest 1-2 days, then bring it slowing down to lagering temps. I'll lager it for at least 6 weeks.

It seems fermentaion has gone quicker than I expected. I've read that diacetyl rest should be started when fermentation is about 75% done. Did I miss my window? Should I start D-rest now or am I better off leting the fermentation finish at 50 and take my chances with diacetyl? Will doing a D-rest now do any harm?

You can start the D rest now, as long as the yeast are still active, they will do what you need them to do.

I kegged once for a week and came back to find a prominent butter flavor in my brew.

I pulled the pressure, undid the lid, tossed in 1 tsp of dry yeast and put the lid back on. Gave it a small hit with gas and purged, re-hit the gas and let it sit outside of the fridge for another week and it was good.

If you do have any remaining buttery flavor you can always cover it up with dry hopping. (I tried that once too and it worked well).