Ideal temperature range for US-05 is 15C(59F) to (22C)71F.
When I use US-05 I ferment at 19C, it is usually ready to bottle or keg in about 10-12 days. This yeast usually finishes around 1.008 to 1.010 for me
For a Porter I would be more inclined to use S-04, and mash at a higher temperature, say 155-156F it should finish a little higher, like as high as 1.018, leaving a bit more residual sweetness which you expect from a Porter. S-04 tends to work a bit quicker than US-05 for me. Personally, for a Porter, I will give a Porter fermented with S-04 a full 14 days to ferment out, and settle, then cold crash for about 3 days. I like to bottle Porters, and leave them to condition at room temperature for a month or four, or more.
Good luck with it!
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