Fear not ... so long as you and everyone around him includesign him in the preparation and makes a huge fuss of him being a big brother once baby arrives all should be well ... perhaps get a gift from baby to give him when you bring baby home and ask that anyone who buys a welcome gift to also remember big brother ... If he doesn't feel left out then you are unlikely to encounter issues ...
eldest was 2 years, 3 months. He adored his baby brother.
I prepared him by showing him photos and videos of babies, himself as a baby... for a few months. He started to love babies! I went on and on about how he was so wonderful I wanted "another one, hoping he'll be just as good as you!"
When the baby arrived, he came home from his grandparents to find me on the sofa ready to give him a very careful cuddle (caesarian wound was very painful but cuddling my boy was worth it), then I pointed at the moses basket "what's in there, love?" his eyes lit up, he said "oooh a BAY-BEEE!" and didn't even notice the present that the baby had for him.
This time around, he's 4 and just said "oh, I think I'd like a new baby, yes!" and his brother isn't as verbal so hasn't been told as much though we do talk about the new baby to him too.
I think 2's young enough not to be jealous, but not to understand why he can't climb into the baby's cot either. DS1 and DD1 were 14 months apart and that was the only issue, that and suddenly deciding that he couldn't feed himself, so I had DD on one boob and was spoon-feeding DS with the other hand simultaneously.
My Dd2 is due 6 days before dd1's second birthday, she's too young to understand the concept of me having a baby in my belly (I'm 31 weeks so dd1 is 21 months now) but we've bought her a baby doll to try and bring out a bit of a maternal instinct and have been pointing out little babies enthusiastically to get her to take an interest.
So far she's quite blase about them and I do worry about jealousy as she's all me at the moment but I plan to make sure she is never pushed away and am going to incude her in the feeding/dressing etc.
A few of my friend have similar age gaps with their children and they've all said its gone smoothly.