No exact date, you must be close with 1999.
The first CZ-USA catalog/brochure I have has no date on it but they were bragging about their 1999 IPSC team silver medal.
I bought my first CZ 550 Magnum .375 H&H in 2000 in KY.
I also found an action-only at Great Northern Guns in Anchorage, AK in year 2000, with serial number AHR 50001.
I always wondered if someone had liberated one from a special batch serial numbering for AHR.
Sleuth it out for us, Karl.