Precision of language, Jonas.I'm new here but I find in my work as an agent, parent, scout leader, human being that some words have specific meanings and when those are the specific meanings that you mean to convey then you should use those words.

Or texas......Cool chart below, really puts things into perspective.

Two masters degrees, two properties and my home residence, and still charting my path to the goals I set sooooo many years ago. 

Most counties have a chart that allows you to figure out these amounts.2) 20% for PM, Vacancy & MNT?

Quicker build times, no external factors (weather), precise details.

Hey @Graham Huber here's a couple charts on Philadelphia compared to other nearby major cities.

The price of real estate there is off the charts and completely insane.

See the chart from Fair Isaac Company (FICO) below: FICO Score Pct of Population Default Probability 800 or more 13.00% 1.00% 750-799 27.00% 1.00% 700-749 18.00% 4.40% 650-699 15.00% 8.90% 600-649 12.00% 15.80% 550-599 8.00% 22.50% 500-549 5.00% 28.40% Less than 499 2.00% 41.00% Source: Fair Isaac CompanyAccording to this chart, investors should use corresponding vacancy+tenant-nonperformance factors of approximately 5% for Class A rentals, 10% for Class B and 20% for Class C.To address Class C payment challenges, many industry "experts" are now selling programs to newbie investors about how Section 8 tenants are the cure.

Sadly, there is no precise “right time” to begin.

The CRASH is for sure coming....Here's how to protect yourself:1) Only buy good deals below current market value2) Prudently escrow the money it takes to get them into service (in service = making money)3) Don't over-extend on the amount of projects you can do at one time (project = time between purchase and "in service")4) Continually build your skills in getting deals (sales/networking/marketing), building a better depth chart of vendors, project management, and writing strategic scopes of work for the properties you buy. 5) Put money aside after every successful project.