Before interviewing: determine either in advance of the conversation, or at the beginning of the interview the current hiring environment. In other words, "are you hiring now, or in the next 30 to 45 days?"
JMJ will interview for the sake of interviewing, not to fill a position.
At the end of the interview JMJ will share their current hiring plans for this year or the next which may include a seven to ten month hiatus of non-hiring. Then why interview?
JMJ does not have respect for your time, otherwise they would push back the interviews until they are actively recruiting so you wouldn't have to step away from your current obligations to speak with them.
Be careful with your time and do not make the assumption it will be time well spent with JMJ recruiters without specific knowledge beforehand.