As a general guideline, you usually don't need a guide to get you started with the game. If you have never before brought a class up through the levels, I would advise against a skip potion, and simply play your chosen class/job to max level.
FFXIV goes great lengths to teach you gameplay and your chosen job. You'll start out slow and the game takes you by the hand, especially at the beginning. There are also Guildhests, which are trials that show you the basics of group play, and there is the Hall of the Novice, where you can learn anything you need to know about a job.
As others have mentioned, if you want to make your character look pretty, there's the glamour system for that - you can exchange the appearance of most items you're wearing with all other items of the same class that you could theoretically wear. Also, a lot of equipment can be dyed with a huge number of dyes and metallic dyes.
How long it would take depends entirely on your play style.
That being said, as others mentioned, if you're looking for p2w, FFXIV certainly isn't for you. Apart from the skipping potions, all other items at the Mog Station are vanity items, such as mounts, dyes, minions (FFXIV's versions of pets), etc.
I'd suggest just giving the trial a go. That can be played up to level 35, with no time limit, and should give you a good idea of what to expect.
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