Hey Hector, I'm new to investing as well, but we had PMI on our home purchase due to putting 3.5% down. Our approach was to do home improvements with the difference of 3.5% and 20% we needed to avoid PMI. So we took the 16.5% and made home improvements in the first year. If I recall (this was back in 2014) our PMI was $200 or so a month which ended up costing us $2400 which was cheaper than putting the full 20% down and we were able to increase the value enough to refinance after the first year and have 20% equity. Note that I live in Seattle and we have seen unprecedented value increase over the last decade or so. For example our home has more than doubled in value according to our latest appraisal since 2014.
Realize there are risks and barriers to this approach. If you're not seeing values increase in your area then you may or maynot be able to get to the 20% with improvements? Additionally if the market turns you could be paying that PMI until you're able to pay your principle down enough to refi. Rates could go higher.
Other options could be to get creative financing. Not that I recommend borrowing money from family, but my father in law and I worked out a deal when we bought our first house where he helped to finance some of the improvements we didn't plan on doing and upon refinance we pulled funds and paid him back with interest. (I'm sure if you listen to bigger pockets podcast you've thought of creative financing!)
Hope this helps and good luck.
Ben