I'm sorry I wasn't quicker to respond, but most HIDs, including factory kits, take a few seconds to reach full output. They have this warm up period to prevent the bulbs from failing prematurely.

If they came on immediately, it would greatly reduce the bulb's lifespan

The warm up period is much less harsh on the bulbs and makes them last a lot longer. There are many more reasons why, but that should help a bit.

Nick C.