There are various factors to consider when incorporating foam rolling into your warm up. From a bio-mechanical standpoint, using foam rolling can improve an individual’s acute flexibility and performance, therefore it would be hard to disregard the use of foam rolling within a warm up routine. However, research would suggest that in order to achieve any significant benefits, you would have to spend a minimum of 15 minutes on a roller, which may not be very practical for some people.
So my advice, if you are pressed for time, is to focus on the main areas that are giving you problems or focus on the areas that you will be using in your warm up and then move on. For example, if you are going to be squatting, then it would make sense to focus on the lower body and back; this way you can still reap the benefits of foam rolling. And, on rest days, you might like to devote a bit more time to mobility work, and spend longer!