My perspective on this is that when it comes to cards (or really any kind of collecting) there are two main mindsets: collect to enjoy, or collect to resell. Sure there are degrees of both, but in the end one or the other is dominant.
Me, I'm an 'enjoyer.' I don't buy things to put them away in the hopes that maybe someday they will be worth more than I paid for them. I buy a thing because I like it enough that I want to use it. I want to hold it, use it, admire it. When it comes to cards, I buy just one of any deck I'm interested in and I open it immediately. I don't really care if it's 'rare' or not. Particularly with cards, if you never open it you aren't seeing like 98% of what you bought.
Now if you are 'reseller' then the primary motivation for collecting things is more on the financial side. You buy a thing not for the personal enjoyment of using the object but because you perceive that with time it will be something valuable. I think this person is more about enjoying the acquisition process, hunting down a rare item, getting a deal, being proud of the collection and then making some money someday.
So what kind of person are you? I'd say most folks fall one way or the the other the majority of the time. Of course nothing is concrete and unchanging, but in your heart you probably lean towards one of those. Find out which, and there ya go.
So, knowing where I come from, my advice is to open it immediately and have fun.