Looking at France panicking because 2 weeks after snap election there isn’t a clear majority, nor a coalition ready to propose a prime-minister to the president. What would be the standard time to do these negotiations in a functional democracy where doing coalition is common but doesn’t take years (so US and Belgium do not coun :) )
EDIT : Need not Name
1-2 months, by law after 1 month there has to be parliament meeting that gives majority support to government, if it don’t give support then another party gets to make government, after that another election.
It depends on the situation, usually the coalition potential is known in advance so it is usually quick.