*** Topic moved from K1 forum to Removing Conditions on Residency ***
No. You must apply for removal of conditions (ROC) form I-751 first, you can’t bypass this step.
When he’s eligible, he can apply for citizenship even if I-751 is still pending.
From what you described it seems like he can apply for citizenship in 2025. Under the 3 year rule, you must be married to a US citizen AND be a lawful permanent resident for 3 years (so you have to count after he had his I-485 approved, not when he came to the US on K1).