S-05, like all yeasts, will be a bit slow initially if pitched on the low end of the ale temp range as you did. But it WILL get going, usually within 24 hours, and it will be fermenting vigorously once it hits the mid-60's.
As for temp change during the lag and growth phase, I'm not sure, but I've read that a drop in temp during this time can increase ester and diacetyl production. Some people recommend starting warmer so the yeast get going quickly and then bringing the temp into fermentation range. Others recommend pitching below the target range and gradually letting the temp rise. And others just try to keep it 65-68 F the whole time. I have had good results with all 3 methods, but I try to pitch ales around 65 F and lagers around 50-55 F.