First of all, there is no rule on this that is being enforced, everybody may do however they choose.
But, usually within the community the procedure is: the שדכן (Matchmaker) calls up both sides (parents) with the idea, the parents will do research, they will try to do the best research, in some cases it will take a week, sometimes more.
Once both sides decide that it could be a match they will first ask the boy or girl what do they say.
Then they will arrange a date, usually it's indoor, in the house of the girl, or a relative.
Because the parents did most of the research, and we trust our parents to know whats good for us, there are not many dates usually, mostly 2 or 3 meetings, once the boy and girl decide to take the next step, we make a לחיים and Mazel Tov...
I think average time between shiduch and marriage is 8-10 months.
But again there is no כללים everything depends on the situation and so on.