22, no debt, income increasing- when to jump in?

[Account Closed]

Hey all! This is my first post. At first I wrote this really long post but it was about 15 paragraphs so I synthesized it into three pretty relevant questions.

If you had $25k at age 22 what would you do with it?
If you had $40k at age 22 what would you do with it?
If you knew next year you would have $75k saved, is there value in waiting to invest it all at once?
Rule: Have to leave $15k in for 6-month emergency fund. You have no debt. Credit score 760.
No equity going into a house at the moment- but have the cheapest rent possible in your area.

Two biggest contenders in my mind at the moment: 
Dump all profits into index funds utilizing some IRA/401k contributions for extra benefit
OR
Save up enough to begin flipping houses- still do 401k to at least matching level
Note: not working a 9-5 job, work all your own hours only have to attend 2 meetings/wk 2 hrs each

Your job is already incredibly rewarding so you are willing to take on extra bs/work in order to compound your savings over time. Not in a rush but want to turn your money into more money.