We’ve done MK EMM from Poly several times. Someone new would never know this, but the stuff you see about boat/ferry/monorail starting 30 minutes prior to park opening is about the most inaccurate info Disney publishes, yet they put it in LOTS of places in different materials. But anyways, monorail hours can change week to week, but generally speaking 7am is a common start time when MK has 9am openings. The weekly Times Guide has accurate monorail times. You can pick one up where there (front of park or often in resort lobbies) or this is a handy link: https://www.orlandoparksnews.com/p/weekly-walt-disney-world-times-guides.html From Poly, we’d usually leave our room around 7am and head to the Grand Ceremonial House/monorail station. You do have to do a security check at the monorail station, but it’s usually pretty quick at that hour. If you’re nervous about transportation, you can always build in more time and just hang out in front of the MK early. One big caveat and/or warning from experience - you do need to have a back-up plan in mind in the event the monorail is down. When that happens, buses are ‘supposed’ to be running from Poly to the MK... but it can be a bit confusing on the ground as to just what to do when/if this happens. Wait at the bus stop and hope one comes? Take the boat (it’s a bit early for a reliable boat)? Other options? Walk over to the MK Ferry from the TTC? All of a sudden the 30-45 mins you thought you had to make it to MK starts shrinking fast! Fortunately, we’ve never experienced the monorail being down on an EMM morning, so we’ve had good transportation mojo and made it to MK each time with little stress. I have had times where I’ve been trying to rope drop MK with similar timing to EMM and the monorail has been down. One time we grabbed a cab and took it to CR then walked to MK. Probably an overreaction on my part and I should have just waited for the bus, but I get nervous/antsy in this situations and like the control of a cab/Uber/etc. Sorry, long-winded answer! I guess the point of story is for Plan B - just have something in mind (taxi, bus, etc) you can execute quickly in the unlikely (but possible) chance you need to.