We purchased four starter kits, I know... don't ask!
1.  140yr Old San Francisco Sourdough Starter from MomsSanFranSourdough on Etsy.
2. San Fran "Wharf" from PositivelyProbiotic also on Etsy.
3. Gluten Free from PositivelyProbiotic also on Etsy.
4. Buckwheat GF from PositivelyProbiotic also on Etsy.

I purchased the 140 year old one first, as the old-time Sourdough sounded ideal to me. We haven't yet tried this one, as it sounds quite precious, but I am excited to do so. I'm sure it will be great!
Second, I purchased the other three from Positively Probiotic. Buckwheat is really the only one I'm allowed on my "Diet" but I have yet to try that one. I figured I'd start with the basic ones, so I could perfect the recipe and then go for the less conventional Sourdoughs, once I knew what I was doing. I purchased the Gluten Free for my Husband who I encourage to eat GF whenever possible.

Feeding and firing up the started isn't complicated, you just need to remember to feed it like a plant or any other living thing, daily. So we fed it to activate it for a total of sixteen (16) days. The reason we did this for so long, was that we were waiting for a bunch of bread-making equipment to arrive that was delayed due to  Covid-19. The items included a Proofing basket with linen liner, an Emile Henry Artisan Loaf baker and a couple of other bits and bobs that I'll cover in the bread making post. 

We followed the instructions that came with our Starter on the Positively Probiotic website.
Read the full instructions HERE, they are very easy to follow. 
It is basically a 1:1:1 (1 part starter, 1 part water, 1 part flour) ratio which is super easy to follow.
Once the sourdough levain is full of bubbles and starts smelling sweet and tangy after day 6, we were ready to go. However, we fed and waited another few days to make our bread.
We placed ours in a glass Weck container, to preserve its purity (don't want any nasty plastics around).

I later found a useful video by Amy Duska on how to make your own Sourdough Levain Starter from scratch. I didn't realise you could do this, til after I had already purchased all my starters. Great! It is just as simple as with a purchased starter kit. I feel that the starter kit is just a more mature version, which may be more beneficial health-wise.