Four sons, five kids in total (that I know of).....
Essential for me: Baby Bjorn. All five of my kids were happy campers in this thing.
Here's me last year. Here's
me over ten years ago. Now, other than noting that my five kids have aged and destroyed me, you'll note no tears on the faces of my spawn. That's because a happy child is a quiet child and they are happy because they are engaged and in a position they can't be in without help. I'm happy because my hands are free to use the remote control, check scores on my phone or hold my beer. I have cooked meals with the Bjorn, tended bar at parties with the Bjorn, lorded over my grill with the Bjorn....seriously, don't worry about how silly or femme this makes you look, you're going to want and need this. Don't get the knock-off, don't get the Euro Wrap...get the Bjorn and just trust me.
Get a good stroller. Don't get the MOST expensive stroller, but get a good one. Try it out before you buy it. Find one with good drink holders, room to store underneath, a retractable roof to keep out the sun or the rain (I'm in Oregon, so we walk in light rain) and make sure you can fold it up with ease to store in your trunk. Jeep makes a good stroller....not top of the line, but solid.
If people ask you what you need, you need gift cards. And you need gift cards because you really don't know what you need right now. But you will after the baby is born. What did we need? Diapers. Diapers, diapers and more diapers. Blessedly, my wife nursed my younger kids, so haven't bought an ounce of formula, but if your wife struggles with breastfeeding, you'll want those gift cards for formula. It's $$$$$$$$$$. Kids can live in onesies and since you're due in April, that means the first few months of his life will be in warm weather. Forget loading up on clothes and as others have suggested, start buying for sizes down the line. They grow really really fast.
Forget crap like Diaper Genies....just throw the damn diapers in the trashcan outside. Forget about a wipe warmer or a bottle warmer for now. You don't need them and if you find out you do, use one of the gift cards you asked for. You don't HAVE to have a changing table either. Use the sofa or a bed. You also don't HAVE to make the nursery of his (your wife's) dreams. He won't remember it and you'll just redo it when he's a 'big boy' at two. For all the money you might drop creating the perfect nursery, use on a good (again, not the most expensive, just GOOD) crib and perhaps a nice rocking chair for your wife to use to rock the baby to sleep or nurse. You can get a nice rocking chair on CL or Offerup. No need to break the bank, but try it out first.
Oh, pro tip: When you change your boy's diaper, point his wenis down towards his feet. Trust me on this. I've been peed on more than Kim Kardashian in a sex tape. You learn from experience, but heed my advice. Tip that cannon down. Also, learn how to change a diaper like a NASCAR pit crew changes tires. Start working on that right now. Fresh air can be an open invite for little boys to fire at will.