Trying to get the 'Revenue Date' custom field to calculate the correct dates

I'm trying to create a 'Revenue Date' field which follows the logic below.. I want the revenue date field to calculate based on the date fields which our CS team edits. The fields (editable date fields) are - Over ride date - Email start date - live date - estimated email start date - estimated G L date

A 5th auto calculated date field (Estimated Go Live Date) which always has a date value (to be used only if the above fields are blank)

So, the logic I’m trying to use is

(i) Is there an over-ride date? If yes, then take this and stop. If no, go on to (ii)

(ii)Is there at least one of ‘Email Start Date’ or ‘Live Date’? If yes, take the earlier of these and stop. If no, go on to (iii)

(iii) Is there at least one of ‘estimated Email Start Date’ and the ‘estimated G L Date’? ? If yes, take the earlier of these and stop. If no, go on to (iv)

(iv) if all the above fields are blank, take the Estimated Go Live Date

I know this looks confusing but its only because the way we calculate our revenue which depends on the dates entered by our CS team of when we are live on the clients site (not the same as the close date of the deal)..