The older and more mature your phals get the more spikes they might potentially get. I have heard of phals 20-30 years old having 8-10 spikes at once! Most of the plants that we all purchase for sale are just "babies". :-) Your plant will just naturally get more and more spikes as it ages and is getting the culture that it likes. Yes, for the majority of hybrid phals the time that they start developing new spikes is approximately this time frame - give or take. The cool night temps is thought to be part of the trigger - yes, I have about 35 of them and have been trying for mid to low 50's at night in my growing area - some of them are starting to spike now. "How cool is too cool"? Do you mean for just the evening temperature or during the day? They could bet down into the 40's or even 30's a couple times without killing/hurting them - but you would not want to do this regularly. They need to be warm during the day or they will stall and not grow - preferably at least mid to upper 70's. They will even grow better in the 80's. Good luck - sounds like you are doing the right things to have a plant setting spikes like you describe. When you get flowers post a pic and brag a little!
mike