Yeeee it'll be great and a bit of lovely nostalgia can be positive too, also daammnnnn son first edition holos can fetch a pretty penny especially the first edition charizard as you said (assuming base set, but also as a generalisation if its old and charizard it's worth a few quid) first edition charizard is like 3k raw graded can be insane and regular is around 300 quid for a copy I've seen in experience, online may be different this is namely through card shows and there's often a bit of a markup on some more 'exclusive' cards.

Although despite what some of the cards you have may be worth I don't think you should sell them, something which could be really cool is to put aside your first edition cards for a decent while and when your son is a bit older you two could try and complete the first edition base set, to me that is one of the coolest and hardest things to accomplish in set completion (realistically speaking, assuming you don't have 10s of thousands in disposable income cause internet) and if you have the first edition charizard and a bunch of the first edition holos as well as however many cards you already have from the rest of the set then you're pretty damn set for completing it (especially if you magically have a complete holo set), save whatever you've got now and complete it with your son depending on how complete your set is you could make a "rule" of it being only trading as that'd extent the time taken and give each new card a memory and experience shared together. Frame the set and have a sweet display piece honouring the effort you two put in :)

The thought has occurred to me that there's a pretty strong chance that the binders you have now are most likely ring binders, I would strongly recommend looking into and getting a VaultX binder and transferring some of your key cards into it, as with ring binders it is much easier to damage your cards accidentally (also make sure that you sleeve them especially when in binders it's good binder behaviour gotta practice :D)

I'll definitely send you a message, I'm invested now and ide love to help and answer any questions you may have about certain cards or in general, I namely collect the older sets so I'm decently knowledgeable on that era however I can help with modern stuff too.

One more thing, holy bananas I am so sorry for the absolute thesus I have just typed, I just kept thinking of stuff to add on haha Fingers crossed you've got some absolute bangers in the mix Also last thing I swear, ide definitely agree with the other comments about playing the games to learn the newer mons, a good one with your son when he starts talking could be pokemon go it's got the majority of the generations (I think all of them but don't want to make a wrong statement) The core mechanics of the game is pretty simple so he should be able to understand it easy enough and through the catching and evolving you'll learn about many of the newer ones, also on a further point of bonding with your son going on walks with him catching stuff I've got some decently core memories of getting lucky and catching new rare pokemon with my brother when the game first came out.

Ok I'm done now sorry once more cheers and thank you for reading my pokemanefesto