Everyone is different. We all have a unique insulin response to carbs. Some guys will get very fat on 200 carbs while others will get shredded. So let me back up. Lets start with protein. For a guy on gear, I would go with around 300-325g protein to start. For fats, you will probably want to start somewhere under 100g. Maybe start with 75g. I would base your carbs off your existing diet. Most guys will be under 200g to start. If you are eating these macros for a couple of wks and shooting pics, you should get an idea of whats happening and then adjust from there.
The leaner you get, the trickier it can get. Some guys need a steady diet of carbs fats and protein. Some need less carbs. Some need low carbs, like a keto diet. Some need to cycle carbs. Its all a big, wonderful experiment, figuring out what works for YOU. If you are interested in fast tracking it and getting some help, I work with guys every day, one on one and would be happy to bring you to the team. If you want to figure it out for yourself, more power to that idea too! If interested, check me out here at Naps, in the Next Level Nutrition section of the site!