imho if you're an early stage startup and you don't have an operations or devops person, you're better off either running everything off a single machine or doing devops the old way (as in baking machine images, updating launch configurations and doing service rollouts with via autoscaling groups).
Once you get more revenue, hiring an operations/devops person might be a good idea. A good operations/devops person might make you save his own salary in infrastructure optimization (depending on the scale of course).
another good pattern that i've seen in action is contracting the operations to an external company that's specialized in doing this. the approach would be to let the external company design and build the cluster for you, define responsibility boundaries for your company vs that company, and let such company take care of daily operations and cluster upgrades, possibly with on-call availability. A small support/consulting package (say, 15-20 hours/month) can get you very far.
We've been doing something similar with SigHup (sighup.io) and their Kubernetes Fury distribution, it's been working very well so far.
(disclaimer: i'm not employed by sighup, just pleased to work with them)