First teeth?

Iliana • V•VIII•MMXVII 💙👶🏼 X•III•MMXX 💙👶🏻

My son is 4 months almost 5 and today I put a finger inside his mouth to see if any teeth were coming out and he has two little sharp bumps on the bottom on each side. Is this normal? I though the first teeth were supposed to be the bottoms front teeth?