When you installed your DDMTuning HID kit and having Auto-On headlights did you need to get a relay like this? http://www.retrosolutionsllc.com/servlet/the-263/Time-Delay-Relay-10/Detail
If you want to play it safe you can use that deal relay. I have heard that turning on and off HID's rapidly is bad for them and may cause them to fail. That might be a good safety net just in case you forget to swtich off the auto on switch.
I always leave my Auto-On active so after the HID's I would really like to keep it that way.
I have factory HIDs, and I always leave the lights on auto. Certainly the manual doesn't say that you can't use the feature that you payed for.
What do you mean the "charge up"? The time it takes to get to color temp?
I'm pretty sure all hids take up time to get to their real color and full brightness. Even my oem ones do. The salt has to heat up and bounce around and then you get your full HID color and brightness