PLEASE DISPROVE MY STRATEGY!!!.... I need critiquing...

[Maxwell Jacas]

Goal: 

1. Retirement for my wife and myself by the end of 2020. (ie. $7000/monthly cash flow)

Plan: 

1. Purchase and Hold inexpensive duplex properties primarily in the florida area.

Breakdown: 

1. Year 1-
2. savings and credit building for  20% down payment, Purchase 1st property in college town, rent out each room for students.

*starting close to home to get my bearings*

1. Year 2- 
2. Save again for another down payment and refinance last property for an additional property, now giving me 3 properties in 2 years time. (all student rentals)
3. Year 3- 
4. Continue the same strategy from the previous years, this time Im purchasing single level duplexes in florida. At this point, Ive saved for another property and refinanced my 3 properties with the intention of purchasing 4 more properties in year 3, giving me a total of 7 properties.

Summation:

If I continue this pattern, I will have 31 properties in 5 years time. 

NOW, PUNCH HOLES IN MY STRATEGY!!!!

Assumptions:

-Property prices: >$80k

-Mortgages per property: $500/mo (max)

-Cashflow Goal: $1000/mo ($1500 rental income - mortgage) *not including reserves for maintenance and any other incidentals

-I will need to have 6 months of mortgage payments saved as well per property.

-Refinancing is done annually and for the appraised value of the property( only need downpayment)

-Refinancing can be done multiple times to the same property yearly. (at most 5 times)

-Refinancing wont be necessary once I have a steady cashflow which will make that aspect of the strategy moot.

Synopsis:

Im sure there is alot Im missing and not considering, this is why I need help.

I like to deal in absolutes, flat out numbers. Im not greedy or really into it for massive wealth, i just want to live the way I prefer. 

It is very ambitious and I have scenarios that are a little more conservative, but I live by the rule, "go big or go home."

I want to make $1000/month cashflow per property after all expenses. I sure there are ways to save money and tricks to do so, but Im here to reach my goal, and if someone is making a little more money from me and its on the up and up, i would be fine with it. I believe I need a great relationship with a bank/lender who sees my vision and no matter the interest rates and percentages, if they can provide the financial support, the end justifies the means.

Thank you in advance.

Max