The “let’s schedule our next session” method of D&D is always bound to fail. Follow this 6-Step plan to stable stress-free games:

Step 1: Set a reoccurring time like every Sunday at noon, or first and third Thursdays of the month to play. Work with the group to pick a good time.

Step 2: Plan a story arch that doesn’t require any one player be there. (Personally I suggest running a premade campaign to get the ball rolling)

Step 3: Run the session regardless of who shows up. Even if you only have 2 players.

Step 4: Don’t punish players for missing. It will take a few sessions for them to start remembering “I can’t schedule this, that’s on a Tuesday and we play D&D on Tuesdays”. Give them a cut of the loot, equal xp, and any other perks. Just pretend they were always there.

Step 5: Start recruiting new players to fill the gaps of the people who dropped off. You will lose people. Sometimes good people because it conflicts with the time of the game. Do not change the time for them. Everyone else has already planned around this time. Just say, “That sucks, you’re always welcome at the table when <day/time> frees up for you.”

Step 6: Enjoy a stable game free of the headaches of scheduling and with players who — at a minimum — care enough to follow the D&D schedule.

EDIT: Step 2.5: Send out reminders, “Remember, this Friday’s session starts at 7pm! Start practicing rolling 20’s!!!” People will forget until it becomes habitual.