Wow, this is a question that will get many varied responses.
I'm in south Louisiana and here's what I do:
Vaccinate and worm twice a year, in the spring and fall. Normally vaccinate with the combos out there (last time I used Virashield VL5) that are safe for pregnant cows. I vaccinate everything, including calves. These vaccines are normally a certain dose (5 cc's) for each animal. For worming I've always used Ivomec plus, because we do have liver flukes down here. I've just recently switched to pour on wormers for the fall worming. I normally apply insecticide ear tags in the spring and pull them off in the fall. I put insecticide tags on calves as well. In the spring working I blackleg.