You'll worry yourself sick asking this question and comparing him to others, OP.
But since you did ask, my DS had very few words at 2. My daughters had been speaking in full sentences at age 2, actually one of them was 18 months and you could hold a full blown conversation with her.
HV wasn't concerned about my DS, said that it's not unusual and that many 2 YOs are just beginning to put 2 words together.
She referred him to SALT anyway, and in his case, the vocabulary did come, but speech was extremely unclear until age 4. He had weekly SLT and fortnightly blocks, with some 6/12 weeks breaks in between.
Meanwhile, friends boys' suddenly began to talk suddenly at 2/2.5, in full, clear sentences. So you just never know.
Your DS might be the very same.
I would never wait around. If you're worried, act on it. The waiting lists are long and the earlier you intervene, the better.
DS made phenomenal improvement with each session. I would never have believed just how effective the therapy sessions are and the 'work' and 'tricks' the therapist will give you to do