Meeting His Parents

My SO and I have been together for 4 months, and I still haven't met his parents. He has met my family countless of times when he comes over. I haven't even been to his house before 😒. He sometimes brings up topics that start with "When you meet my parents..." or "When you meet my mom/dad...." but it never gets to that point. I've asked him before why I haven't met them, and he never really answered me. Is it okay that I haven't met his parents yet? Should I just wait until the time is right?