Man, what are you on about?
The room Lex and Scar enter is exactly the same room as the people got facehugged initially - the sacrificial chamber. You can see the equipment left by the team around the hive - In the very picture you posted, Xhan! - which, if you bother checking, will match the same equipment the people left in that room before the shit hit the fan.
We don't know what the hive crap is, nor do we know how it's made, so it's impossible to say how long the process is, especially since beforehand we were never given an indicator in the previous movies. On top of that, it's not like they hived up a particularly large area; a single chamber, and a part of the adjoining corridor.