
If we have deals with closed date in July, when we are week 1 of that month, the % is 75%. When it is week 2 in that same month, the percentage drops to 50%, week 3 25% and week 4 is 10%.
This way, if a deal has an oppy amount of $1000, on week 4 of the month, the formula field would show $100 on the oppy page.
Also, I want to make this formula apply for only specific opportunity stages. so if I have oppy stages of:
Lead
Discovery
Proposal
Verbal
Closed-Won
I want the formula to only apply the weighted value for Discovery through Verbal. Obviously Closed-Won should be left as is, and Lead we do not want a part of this weighted value.
I searched around for various formulas to see how to get this to work, but can't get it to evaluate what I want. Any ideas community?

I figured it out! here's the code I used, for anyone else with a similar problem. I'm sure there is a more elegant solution, but here's how I got it done (using our Oppy Stages)
IF(OR(
ISPICKVAL(StageName,"Go/No Go"),
ISPICKVAL(StageName,"Propose"),
ISPICKVAL(StageName,"Negotiate T&Cs"),
ISPICKVAL(StageName,"PO System")
),
CASE(Day(TODAY()),
1, Amount * 0.75,
2, Amount * 0.75,
3, Amount * 0.75,
4, Amount * 0.75,
5, Amount * 0.75,
6, Amount * 0.75,
7, Amount * 0.75,
8, Amount * 0.50,
9, Amount * 0.50,
10, Amount * 0.50,
11, Amount * 0.50,
12, Amount * 0.50,
13, Amount * 0.50,
14, Amount * 0.50,
15, Amount * 0.25,
16, Amount * 0.25,
17, Amount * 0.25,
18, Amount * 0.25,
19, Amount * 0.25,
20, Amount * 0.25,
21, Amount * 0.25,
22, Amount * 0.10,
23, Amount * 0.10,
24, Amount * 0.10,
25, Amount * 0.10,
26, Amount * 0.10,
27, Amount * 0.10,
28, Amount * 0.10,
29, Amount * 0.10,
30, Amount * 0.10,
31, Amount * 0.10,
0),
0)