Why not just use formulas in the second row. Adding one to a date  value
gives you next day. Assuming you've derived the Monday by either setting
the cell's display format appropriately or by using the Text function from
the date in another column, then it should be OK too.

It might also be possible to use the fill-down facility to do this. I don't
use it much, so am not sure about this.

you can try to do this with iterations.

This is a bit tricky but doable

No macros involved just excel option settings for calculations should be
set to iterations on, number  of iterations to 1 and manual calculation
set to on.

Step 1

Cell A2 = if(A1=A1,A1+1,)
Cell B2 = IF(B1=B1,B1+1,)
CEll C2 = B2; Here in the format of the cell  customise it to [$-409]dddd.
This will ensure that you get the day part for the corresponding date.

Step2

Cell A1 = 89 ; Starting number
Cell A2 = 1/1/2000; Starting date

Step 3

Press F9

Step 4

Cell A1 = A2
CEll B1 = B2

You are now good to go.

For the automation process you just keep pressing F9. and everything
increases by 1.