When to introduce the "meat" dishes?

My baby is 6.5 months. He has been on solids since 4.5 months. At our 6 month checkup the dr told me to switch him from Gerber 1st foods to Gerber 2nd foods. I see the 2nd foods include several beef, chicken, turkey meals, etc. Is it ok to start introducing those in addition to the fruits and veggies? What age did everyone else start these with their babies?