How long does it take for a team-match to start?

I'm an admin for a rather small group, but with a fairly high average rating.

We are a pretty new group, so we have only 4 matches going with the whole group involved (smaller matches with only 2 players are played as well).

We now wanted to start a fifth teammatch and for the first time there were some problems.

Two times, our challenges were accepted, we joined, but after 3 days only one player of the opposing team has joined. The first time, it was then aborted by them, the second time, it was aborted by us.

Is it normal, that it takes this long to start a team match?

Additionally, because the challenges were unsuccessfull, we challenged groups from the leaderboard, but they didn't answer the challenge even after a few days.

How long should we wait?

Regards

I would just message the other team.