Simple Nested IF based on todays date

Hello.

I have 12 columns each one based on a month… I currently have a total column adding up all these but I only want it to add if we have passed that date.

Here is the formula in the main sum column:

SUM({(01)Apr-2023},{(02)May-2023},{(03)Jun-2023},{(04)Jul-2023},{(05)Aug-2023},{(06)Sep-2023},{(07)Oct-2023},{(08)Nov-2023},{(09)Dec-2023},{(10)Jan-2024},{(11)Feb-2024},{(12)Mar)-2024})

Calculation of that month column should only be included if on or after the 1st of that month. So as of today I would not want {(08)Nov-2023},{(09)Dec-2023},{(10)Jan-2024},{(11)Feb-2024},{(12)Mar)-2024} included.

I can only image doing quite a large nested If statement but I have seen many suggestions not to use nested IF.

OR ALTERNATIVELY if someone can help me figure our how to change the formula under each of the months which is currently for {(01)Apr-2023}:

IF(AND(DAYS(“2023-4-1”, FORMAT_DATE({Deferral Start Date})) >= 0, DAYS(FORMAT_DATE({End}), “2023-4-1”) >= 0), {Invoice £} / {Term}, 0)

… maybe I could tailor this to only do the split calculation if todays date is on or after the 1st of April. I could then easy change all the other columns as it is only the date that changes above and I can add the formula change given.

Any help would be much appreciated.
Many thanks
Lisa