Looking good man, you've got a lot of mass all around! Again I'm no expert by any means, but just my thoughts you're in a good place to start a prep.
As you continue to plan to possibly do a show, tracking macros is a great idea so you can start making progress right away when you begin to cut. Maybe start by taking your best guess of what you're eating, or should be eating for maintenance, and start there. Be very consistent for a few weeks, take pics once a week in the same poses (learning mandatories would be really helpful here), see how your body looks and check the scale. Then you can keep tweaking, so once you start your prep you'll know what to do to start cutting right away.
Just a comparison, before I started my first prep back in January with Stu, he put me on a meal plan in October so we could try to gain a little mass and bring up some weak points before we started cutting, but also to figure out what my maintenance really was. Up until that point I tracked loosely but never was super consistent, eating the same macros for the day as prescribed without any deviation. We did that for a few months, and it was very helpful and informative. Once we started cutting in January, we were able to see movement pretty quickly as we already knew where to start.