How long do 'new' EPs take to go on sale?

I tried doing a search for this and couldn't find any answers, sorry if I missed something. But I was wondering, how long does it usually take before a new expansion pack goes on sale? Does it take a year or something? I've never waited for a sale before, but I feel like that might have to be the case with Horse Ranch Expansion.. so was wondering for those that usually wait for sales to get EPs/Packs if anyone knew the time frame. Thank you very much!