It’s normal for kids to have different pace as their peers, especially if you’re comparing a Dec baby to a Jan baby. Give your LO some time and let him surprise you with what they’ve learnt in school.
I am a SAHM and I only sent my girl (Dec 29 baby) to school at 2.5yo. Just like you, during school tour, I saw her classmate having a conversation with her teacher and I’m like woah (at that point my girl isn’t as advanced as her but could still express herself using simple words).
Fast forward 7 months in school now, she surprise me with new words every other day and could also speak in full sentences. She can also have a conversation with me on what she or her classmates did/ate in school. Sometimes during pick ups, I see her sitting like a mini adult having conversations with her friends like in coffeeshop (shake leg, hands up on table and giggling).
Don’t doubt yourself, you’re doing a good job. It’s normal that we often want to help them when they are struggling because we are the mother. Take this time to loosen up and let him try, they may struggle, they may cry, they may take multiple attempts but they will eventually get it. You can help him by encouraging him and giving praises to let them feel confident, overtime with that confidence, they will attempt to try out more stuffs on their own. 😊