Really depends on the game & how familiar you are with construct ... i use it daily for work and i can bang out a game in a couple of hours or a couple of days depending on whats involved ...
but on the flip side, my personal games take a lot longer as im doing all of the artwork / music / design / sfx AND code all on my own, and theses games are more level oriented, rather than the "choose the right answer / drag -n- drop" things i generally make at work.
the more assets you need and the bigger the game, the longer it will take... (obviously! lol) ... but you can really move quick in c2 once you get the hang of it and have your ideas and assets ready to go!
i came from FLASH... and i havent looked back, seriously the best $129 i have EVER spent!