took 3 weeks for me. but those damn HID kits just would not stay on. they would be on again, off again no matter how much i tinkered with them.
alot of people (many of my friends included) have had great experiences with the DDM kits and say they've never given them any problems. one of my friends has a DDM kit in his camry for 3-4 years now and never once have they given him any problems
BUT for me, they just kept either turning on or off. I compared my DDM ballast with my friend's (camry) DDM ballast he got a few years back and mine looks straight up like made in china crap that looked really weakly made. Seems like their quality has really gone down since then.
I ended up getting rid of the DDM kits on craigslist and getting a set from xenon depot (vendors on this site). They were a bit more expensive, but I haven't once had any problems whatsoever with that set. I would recommend those that are considering DDM kits to go elsewhere, spend a bit more money and get a more reliable, trusted product.