Have a drink on me you need it after my endless waffling!
We are used to it. Honestly, its better to waffle now with a cycling tank and get the right fish when the time comes... than to go full bash with the wrong fish and then regret it after you find out and you have an uncycled tank.
We've seen situations where someone comes in and says they have a 15 G tank like yours, have a bala shark, a common pleco and a dozen other fish, and can't seem to figure out why their tank isn't working out the way they'd hoped.
There's this deep-rooted misconception that fish only grow to the size of their container... and that is so far from the reality. A big fish in a small tank will not grow as big as it would if it were kept in a larger container... that's true. But... the reason is that it will grow deformed and die at a young age. Its very sad. Its the equivalent of keeping a great dane puppy in a 3 foot cube... it just doesn't work. These animals are our responsibility and we need to do the very best we can for them, as they entertain us with their antics... and frankly... their antics will be far better when kept properly.
For example... I've been a fan of tiger barbs since I first laid eyes on them as a pre-teen. BUT... they weren't suitable for the other fish we kept, so they were always on the 'No' list. It was sad. But, this year (just a few months ago, actually) my old stock had reached a sufficiently low number that I thought it was time for a change. So, my remaining 4 tetras moved out of the 55 gallon... and into a 15 gallon retirement home. And my 55 gallon was turned into a tiger barb tank. I now have tigers, rosys and a rainbow shark. Lovely tank, very active, but the fish are appropriate together.
The point: You will have many many fish in your lifetime. Waffle here and there, but always keep the fish that are appropriate for the tank (and tankmates) that you have. BUT... keep that wish list in the back of your mind for when you get a bigger tank, another tank, etc. This hobby is highly addictive, and the more you know about the fish out there, the more you want more tanks and more of them. This is just the tip of the iceberg for you. And just because you can't have all the fish you fall in love with today, doesn't mean that you never can. I waited over 25 years for tiger barbs.