It is fun but it can also be a headache when you run into scheduling conflicts. A friend and I have run into this with just 2 of us to worry about. I'm sure it would be worse trying to coordinate 4 people. No matter someone's good intent when they agree to an initial schedule, things inevitably happen so they can't show up and that ends up delaying everyone's progress.

If you want reduce possible stress, make certain everyone is in agreement upfront and willing to be very flexible about how fast the group progresses. There should be no set goal of completing content within a certain time frame.

Only alts made specifically for the group should be used so everyone can progress separately on their other characters at their own pace.

Pick meeting days/times that can be adjusted if someone needs to be late or leave early (not a good idea to schedule a 6:30 start time if someone normally doesn't get home from work until 6 but occasionally has to work overtime or gets stuck in traffic).

Some members leveling up faster than others shouldn't be a big deal considering everyone would be blocked by the same MSQ progress. If you feel like level differences might create balance problems, you can always ask everyone to limit equipped gear to items intended for the MSQ level or lower.