If you built your time using the CFI route, make sure your personal currency is where it should be. Airlines will teach you everything you need to know. They expect you to be instrument current and proficient. If you are struggling to fly at an ATP level in your current aircraft, you’ll struggle in simulator training.

I tell instructors to grab an other instructor and go fly. Borrow or rent a plane. Fly at night under the hood or actual IMC. Fly IFR to an airport more than 50 miles away. Shoot 3 IFR approaches including a full procedure to 2 missed approaches and holding and then land out of the last approach. Switch seats and do the same on the way back to your home base. If you will do this once every month or two, you’ll be far sharper than most coming into initial training.