The dress is awesome - definitly buy the dress.
BUT whether to wear it on a first date depends on the context because the dress is very seductive and full on. It's a dress to impress and that is obvious.
You don't say more than he's a friend of a friend or how you know him/how long you've known him/context of the date/ your normal dress style/how well he knows you.
SO:
- If this is not your normal style, I'd avoid it for a first date because it is so seductive you are unlikely to feel comfortable and relaxed.
- If this is a near blind date/date zero and you don't really know him, I'd avoid it because it will look too try hard and frankly might scare him off if he turns up in smart jeans.
- If this more of a "we've known each other for ages, I like you, you like me, big build up and tonight's the night" type date, then I'd go for it. It shows you are trying to impress him and are making an effort.
Really there are three key factors - one is about you: - are you going to feel comfortable in this dress at this stage of your developing relationship?
one is about your relationship to date with him - is this a test the water date with no expectation? or is this much more we know we like each other date?
and the other is about the message you are sending at an early stage: is it too try hard at this stage given your "relationship" to date? Do you want to have some where to go in terms of pulling out all the stops to look even more spectacular if this is just an early stage?do you normally dress in this style so that it wouldn't be unusual? Or would it be exceptional for you and would he know it?
Don't overthink any of this. Your gut will tell you whether to wear it or not.