I have the same question as @OurJud, but if you're asking if that's right? I would say: "Okay. I'll wait for you on the other side," he replied. I prefer the speaking part at the front, tag at the back, and it annoys the hell out of me when people don't spell out 'okay'. That's just an opinion though.
I want to make sure that I get the dialogue the right way around rather than the wrong way around that would put off a potential agent/publisher
Right way round in what sense? I'm not being purposely awkward here, but we're not mind-readers. I agree with @Trish, but only in as much as I prefer the tag at the end. But there are no rules for this - both are fine.
You have capitalization, spacing, and punctuation issues here--issues that you don't have in your post; it appears from your post that you do understand capitalization, etc. It would be best for you to make your samples as correct as you can, so that we have a better idea of where you're having an issue.
This is what I found online to show you how it should look on the page. http://firstmanuscript.com/format-dialogue/ Basically: double quotations outside of the spoken text, proper indentation, and punctuation within the quote.
There's also: "Okay," he replied. "I'll wait for you on the other side." Which is more of a beat. But that really depends on if your character is pausing between those two points. @Trish's is more sure and mine is more tentative, so it's important to know how your character is feeling at that moment they speak.