My time to ejaculation hasn’t changed since my circumcision. Is this normal?

It’s tough to say for sure, but I suspect this is a transient effect of the circumcision. The head of your penis is now exposed and likely quite sensitive. With time, the sensitivity should decrease. In the meantime, it is safe to apply an over-the-counter steroid ointment 15 minutes before intercourse to reduce the sensitivity of the penis. Just wipe it off before actual intimacy.