Neck Sweating

Got a couple of heifers that could I'd like to tighten up in the neck.  is it better to sweat them gradually over a long period of time (like 6 weeks), or are we better off with a 10 - 12 hour regimen a week or so before showing?  I have the neoprene sweats from Sullivan's, and the hot sweat lotion.

I like to sweat them 4-5 days before the show. 12 hours at a time.  I do not like the lotion, we do not use it.  You will see a difference within a couple of days. 

I like to start about a week before the show especially this time of year due to the heat. We'll use the lotion or something similar a couple days before the show and at the show. But be aware that lotion can cause some flaking of the skin on some animals. Use plenty of Revive on their necks after washing out that lotion if you use it.