Don't overthink things. Just keep reminding yourself that as long as you & your OH and the officiant and the witnesses turn up at the right time, that's all that really matters. It's easy to worry about every little thing, but I found it helpful just bringing everything back to the basics!
E.g. yes, it would be sad if your engagement ring doesn't arrive in time for the wedding...but it won't stop you getting married, and in 5 years time, you probably wouldn't even remember that you hadn't had it for the wedding.