Definitely a good idea to get FP+ for 7DMT. Note that they could be all gone more than 30 days in advance.
Besides FP+, first thing in the morning is best. Get there early, no need to run, follow the crowd, stay to the right around the castle. The line will look ridiculously long, but because no one will be using FP during EMH, the line will move quick. On our last trip, we were there at rope drop, did not rush, and only waited 10 minutes. Another morning, we didn't get out of our ADR until 9am, but the park had actually opened around 8:45am, we waited about 25 minutes.
Other best bet is right before park close. Posted wait 40 minutes standby, 10 minutes before park close, we could see the line was much shorter, only waited 10 minutes. Again helped because no one is returning with FP at that time.
Also interesting, we were also surprised last trip that 7DMT continued running in steady rain. CM said they will only shut down for lightning in the area.