New to STRs/Real Estate Investing. How to build portfolio?

[David Taylor]

Hello and good morning. 
I’ve been lurking here for a while - trying to educate myself as much as possible - but this is my first post. 
A little background: my wife and I are both in our mid-40’s. My wife has worked as an administrative assistant for much of her adult life, and I’ve been working (for over 20 years) in ophthalmology (Retina specialty), as a technician and biomedical photographer. It sounds much fancier than it is. 
We spent the first several years of our relationship (and marriage) helping each other get out of debt. Besides a car loan, we’ve had no “revolving debt” for the past 3 years. We have wanted to get involved in vacation rental properties for several years now, but never truly took it seriously because of our previous debt difficulties.  We have been saving up for our next step (whatever it ends up being) and have around $20k at this point - adding around $1,500 each month. We are both disgusted with our jobs - and are tired of making someone else incredibly wealthy, while we toil away. We are currently living with my parents to allow us to maximize the amount we can save. 
Put simply, we don’t know exactly where to start. Since we are “rookies”, we don’t even know what we don’t know, or what questions we should be asking. 
We are setting up appointments with banks to determine what exactly will be (financially) expected of us when we are ready to move forward. Questions as simple as “what % down for a rental property?” are high on our list. Then we will contact real estate agents in the areas/regions we are interested in to dive deeper and (hopefully) get insider knowledge of local regulations/sentiments regarding short-term vacation rental properties, as well as using tools such as AirDNA.

My current plan (albeit, naive/ignorant?) is to use our savings (as a down payment) to invest in a single family home/cabin in one of the touristy areas within a few hours drive of our home. After some research, 50% occupancy seems very reasonable - with many places sitting around 75% or higher. We would use the profit from this first property to reinvest in another property, then continue to snowball this method into allowing us to quit our current jobs/work towards financial freedom. 
While I haven’t ruled out alternative financing options, at least for the short-term (due to our limited experience in the real estate market), it seems more appropriate to deal with traditional forms of financing. 
I know this was a long intro, but I’d love to hear critiques of my current approach - or challenges to this mindset. If you have any advice or resources, I’d greatly appreciate it. I’m certain this has been discussed on these forums before, but a quick search didn’t point to much recent activity. Questions involving “time frame“ - such as “how quickly can you typically use the profits from a rental property to invest in the next property?”, come to mind. 
Regardless, I’d love some feedback and/or pushback. Thank you for your insight and consideration!