When is it appropriate to start using pet names?

My boyfriend (28m) and I (28f) have been together for almost 6 months, and for the first 2-3 months I couldn't get myself to call him by any pet names. I have no clue why it was so awkward for me. I, of course, do now because it feels normal now but did anyone else experience this? Haha. Or am I just weird?

Edited to add another question: What are some of your favorite pet names to call your partner or to have your partner call you?

(Side note: I am in love with this man, and he was very patient with me when it came to this and it never caused problems. I'm just asking to hear other how other people feel/handled it)