So my astronomancy, which I use for large rituals, goes as follows -
Call the attention of the coven together, call for focus, call for the invocation of the coven bond. Witnesses are asked to bear witness etc.
The sign we are to invoke is laid out and described, impressed into the area we’re using to cast / the regio. Usually a casting leader asks questions of the contributors to describe the sign in Socratic fashion.
The mana is brought into the sign and used to empower it.
The sign is raised to the heavens, usually by chant: AS WE HAVE ORDERED THE EARTH, SO LET THE HEAVENS BE ORDERED.
The regio or casting area is then made into a symbolic representation of the area to be targeted. Usually this involves a map: it also involves a symbolic permission from the owners of the area, for example a formal invitation from Varushkans.
Then the sign is called down upon the regio, usually by chant: AS THE HEAVENS ARE ORDERED, SO LET THE EARTH ORDERED BE.
This having been done, the coven come together: they acknowledge that they have seen the thing, that it has been witnessed, that it has been done. A formal question is asked: ARE WE DONE HERE? And the formal answer is given: IT IS DONE.
Then we break, step quickly out of the circle, and check one another immediately for injuries, curses, tulpa or other signs of fail.
If anything comes in to fuck the ritual up, we have a defined emergency procedure whereby the primary caster attempts to close the ritual up and stop doom from descending while the other casters gtfo and someone calls a medic. (OC, a failed ritual is an excellent bit of fun and I wanted to have a defined procedure for signalling to a ref that we’d fucked up and wanted some trauma cards to go with our magic.)