Whenever someone proposes a topic on https://om.rs/designtime that needs to be scheduled, we reply in a new topic (see HOWTO at https://om.rs/offtopic) to work out timing arrangements (see this post as an example of best practice):
When 3+ people’s schedules need to be coordinated, create a doodle poll of upcoming available design forum slots and let them work it out.
Leave it up to the person requesting the design forum to ensure enough people have confirmed before we schedule (and announce) the forum. If they can’t get people to complete the doodle poll, then there’s probably little chance they’re going to get them all on a call together.
Announce design forum topics not fewer than 3 days beforehand (by Monday for a Wednesday forum and by Friday for a Monday forum).
Ensure the time of the call is included in the announcement
Quote the proposal in the announcement, changing “required attendees” to “ATTN”. See this post for example of best practice. This allows people to see a brief description & objectives for the discussion, who proposed it, and calls out attendees yet again.
Extra credit: revise the OpenMRS calendar (om.rs/cal) entry for that design forum to include the topic and description. May not be necessary, but a nice touch and might help people with timezone dyschronometria.