United's sim check is in an EFIS 737, so if you have been flying nothing but trainers or pointy noses then maybe the lower cost non NG type is a good idea if United is on your list of companies you want to work for in the industry. You can also do a 1 hour sim prep ride in that type of sim much cheaper. One of the big differences between the military and a job hunt is there are no written rules just guidance from each specific company, rumors on the Internet, and what you feel best preps you for getting the job you want. IMHO, you want to do all you can do ahead of time rather than find yourself asking how long until you can interview again.