How long is not long? A year is different to 3 years is different to 5 years. The thing about the pre-children years of your relationship is that these are the foundation to everything else. The time and effort you put in now is the investment to everything that will come in the future.
Fwiw, Dh and I were together 4.5 when our first was born. I was 32 and she was carefully planned for a career break for me, hence the timing. My 2nd was born at 37, also carefully and intentionally planned.
You also never get this time back. And it won’t be anything like this again until dare I say your children (all of them, not just the first one) move out and are living independently. So no weekends away just the two of you, no dinners out every week, no lie ins, no sex regularly and spontaneously for a good 20-25 years.
Now yes, you will go to dinner together alone again, but it won’t be regularly and it will require military precision to organise and possibly cost you £12 a hour in a babysitter. Having a child isn’t fun. That’s not to say it isn’t lovely. Mine are 8 & 13 and I am very grateful for them and Dh and I have a solid and happy marriage. But there is pretty much never a time when I had young children when I was like wow, this is so much more fun than those years when we had lie ins and read in bed with coffee and hiked 15 miles and went to the pub and then out to the cinema on a Saturday. I’m glad we have a family, but I wouldn’t call it fun. It’s something our relationship is solid enough to withstand and our kids are lovely and wonderful.
There will be time. If your fertility is good, it won’t matter waiting a few years. If it isn’t, it’s going to be hard anyway, so wait and enjoy these easy years now. There is no need to rush headlong into years when you barely see each other or speak as you had a screaming toddler off between you and rush out the door. It’s not all cutesy clothes like in the movies. It’s genuinely hard work and your relationship and your own needs go on the back burner for the best part of a decade.
It does come back and get easier, if you’re still together (which probably 50% aren’t). But do not waste these years because this is the battery you charge to get you through until you come out the other side. But make the most of it. Dh and I went travelling in Asia. We are ate at all the restaurants. We had lazy days. We spent a lot of time together planning our life, talking about our values, long term goals. We really put the time in and it’s paid off.