I can see an aweful lot of posts about optimum builds and how you have to take this or that to even have a functional build but I'm wondering if character creation and progression is really that imperative or if people are being a touch dramatic?
This really really heavily depends on your group. If no one is optimized, that is totally fine, as long as everyone is even. If only one person is optimized, that's still pretty okay - they'll get more of the "glory" but it shouldn't be a problem. But if you have at least two optimized characters in your party, and you yourself are not optimized, combats can get really frustrating. When combats last over an hour, and you feel like you are just not contributing anything in combat after combat, it is really dispiriting.
A lot of new players think "I'm OK with being not great at combat, I'm more interested in making a cool character." But I think they often underestimate how large a percentage of the time you spend playing Pathfinder will be in combat, and also underestimate how dispiriting it can be to feel like deadweight over and over in combat after combat. So I would definitely recommend making your character at least "viable" on the "underpowered -> viable -> optimized" scale.
That said, with witch it is pretty straightforward to become viable - all you need is Evil Eye, Cackle, and maybe Misfortune. Then you can do whatever you want with your spells and the rest of your build, since Evil Eye and Cackle will mean you are never going to be deadweight (at least against enemies not immune to mind-affecting, and Misfortune helps against those.)
So honestly I would recommend against that. Flavor-wise, you can definitely have a cauldron and use it as you wish, but I wouldn't take the actual Cauldron hex until later on.
Two reasons: first and foremost, low-level prepared casters like witches have very few spells, and you'll run out real quick. Then you'll be left taking potshots with a crossbow, which I assure you is not very satisfying.
The brilliant thing about witches that makes them such a great class is that your hexes never run out - you can use them over and over all day long. Taking a non-combat hex like Cauldron is really gonna handicap you in that regard.
So I'd highly recommend moving Evil Eye to level 1, Cackle to level 2, and then you can take Cauldron at level 4. Again, you can actually have a cauldron, and you can even use it to create alchemical items if you take Craft (alchemy) as a skill, but you just won't have the Brew Potion feat until you take the Cauldron hex. But finally getting to my second point, you probably won't have tons of money to be crafting potions at those low levels anyway, so getting Brew Potion at level 4 instead of level 1 should be just fine.