If you wish you go into your Teams meeting or lecture a few minutes early and put up a 'welcome screen' to do this:
Create a PowerPoint slide informing the participants the session will begin soon, with any further instructions (such as please mute your microphone).
Example for lectures:
If you wish to use this template, please feel free to download it here:
You can amend it to suit you, and it also comes with a Session Plan slide if you wish to use it. (this could be amended for meetings and the agenda displayed on the Session plan)
If you click to go into the meeting or lecture a few minutes early, you can then share your screen by clicking on the Share content button on your control bar (this is the button with an up arrow)
Choose your Desktop or the PowerPoint you are sharing
You will then see a red line around your screen, this is the area the participants can see
You can then play the PowerPoint to just show the splash screen slide and when your participants join they will see this, be reassured the session is starting soon and will know to mute themselves in advance.