They are always very reliable - the posts were about Darien North where 2 of the 4 pedestals were out for about a week due to the supercharger cabinet being hit by a truck.
You will be stopping at Darien South which has 4 pedestals right next to each other. Never seen a wait there (I pass by regularly), though sometimes you may be paired.
You are traveling at a REALLY bad time for traffic. At that hour from RI I would suggest leaving an hour earlier, cutting over to the Merritt at Milford, going over the TZB instead of GWB, and down the GSP to I-95. My suggested charging would be any/all of Greenwich, Cranbury, Newark, and Aberdeen which are all right on the highway - if it were me I would charge a little in Greenwich to make it to Cranbury, and then enough at Cranbury to get to Aberdeen where I charge to 90%. You can easily get to DC and back from Aberdeen, and Laurel is a good fallback on the way home if you are feeling anxious.