How to run Combat for D&D 5e
Here's another way that might work, if you have the right players: make all the mechanical bits visible on the surface.
When a fight breaks out, go ahead and roll initiative for everyone. Unless someone has an ability that is used during an initiative roll (and to my knowledge, there aren't any in 5E), or some way to alter their roll, there's no reason to have to wait on all the players to roll their own.
Consider grouping enemies together; if there are four goblins and a bugbear, you might want to just make one roll for the goblins and have them act as a group.
Post everyone's status in a table, using the Easy Table. (You can find how to make them in the Help page.) Keep it simple, just list every combatant in order with their AC and hit points (and maybe saves) and a section for any status effects. This way everyone can see who is in what shape. Don't bother hiding monster hit points, that just slows things down.
Whenever a player posts their action, they should be able to tell success or failure immediately because you've posted all the enemies' defenses. Let the players roll everything they need to write their actions up, including enemy saving throws. Have them post the results, and copy-paste the table at the end with the effects added in.
If they do it this way, and post frequently enough that everyone can post in their initiative order, then each player knows the current state of the fight when their turn comes up, and you don't have to worry about conflicting actions or people left hanging because they don't know if they hit or not.