Help me get the day of the week correct Sometimes, I will think it is one day of the week (e.g Friday) when in reality, it's earlier in the week (e.g Tuesday).
Your challenge is to display the number of days my estimates are off by.
Challenge
Given a day of the week I think it is, and the day of the week it actually is, output/return the number of days between the two.
Test Cases
Incorrect date, Actual Date -&gt; Days between
Monday, Monday -&gt; 0
Friday, Tuesday -&gt;  3
Saturday, Sunday -&gt; 6
Tuesday, Friday -&gt; 4
Thursday, Wednesday -&gt;  1
Monday, Friday -&gt; 3

Rules

Dates have to be taken as the actual date name (Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday). This is non-negotiable.
Date names must be taken as strings or equivalent in your language (ADTs aren't allowed unless they store their values as the allowed strings)
Input and output can be given/taken in any reasonable format.
Full program or function - it doesn't matter.

And finally, this is code-golf, so the answer in each language with the fewest bytes wins.
JavaScript (ES6), 48 bytes
Expects (day1)(day2).
a=&gt;b=&gt;((g=s=&gt;parseInt(s,34)%72%23)(a)-g(b)+21)%7

Try it online!
How?
We need a hash function \$g\$ that turns a day string into an index. The results of this function are actually quite flexible:

They can be in ascending or descending order: 0,1,2,3,4,5,6 or 6,5,4,3,2,1,0. (We'll have to compute either \$g(a)-g(b)\$ or \$g(b)-g(a)\$ accordingly.)
Day #0 may be any day of the week. For instance, 3,4,5,6,0,1,2 or 4,3,2,1,0,6,5 are also valid.
The results may be greater than \$6\$ as long as they are correct modulo \$7\$. Because the sign of the modulo is the sign of the dividend in JS, we'll have to do something like (g(a) - g(b) + k) % 7 anyway, where \$k\$ is a large enough multiple of \$7\$.

The following function was found by brute-force:
g = s =&gt; parseInt(s, 34) % 72 % 23

which gives:
 day         | base34 -&gt; dec | mod 72 | mod 23 | mod 7
-------------+---------------+--------+--------+-------
 &quot;Monday&quot;    |      30369728 |   56   |   10   |   3
 &quot;Tuesday&quot;   |    1358300452 |    4   |    4   |   4
 &quot;Wednesday&quot; | 1702996445748 |   12   |   12   |   5
 &quot;Thursday&quot;  |   45612914380 |   52   |    6   |   6
 &quot;Friday&quot;    |      21127508 |   44   |   21   |   0
 &quot;Saturday&quot;  |   43748842416 |   24   |    1   |   1
 &quot;Sunday&quot;    |      38623568 |   32   |    9   |   2