This is discussed here many times so I summarize:
Kodak RA-RT chemicals work in room temp, dev 2 minutes, blix 2-4 minutes. I use these times in 23-25 deg C but PE says even 20C is okay (and suggests the mentioned times). I've not used any starter, just the replenisher, as PE suggests. The results are perfect and no-one has ever reported any problems here with Kodak papers.
However, it is said that you may not get perfect results with Fuji papers in room temp.
Of course the higher the temperature, quicker the process. My room temperature is never 20C but rather 23 to 25. Maybe we have powerful house heating systems here.