The Time of Sending the Invitation Message
If your assessment is scheduled for a few days from now, you might not want the participants to receive their invitation just yet. The moment of sending the invitation takes into account a parameter set among the company options.
On the company Options page, you can modify the parameter Delay before sending the invitation:
As indicated by the help bubble, this is the delay, in minutes, between the sending of the invitation and the opening of the assessment.
So, if you enter 30, the invitation will be sent to participants 30 minutes before the opening time.
If, at the moment you launch your invitations, there are less than 30 minutes before the opening, the invitations will be sent immediately.