I’m an event organiser

All my events details are stored in an airtable base.

I’ve created a Zap to send an SMS to my event hosts at d-1 (brief) and d+1 (debrief) 

I’m currently stuck as follows :

If the trigger is “new airtable entry” the maximum delay allowed by zapier is 1 month. Sometimes my events are booked months in advance so the delay for d day is more than 30 days > stuck

So the good trigger may be “updated record in airtable”

Let’s break this down :

The airtable entry exists, and i add a filter : “continue if the pdf file “roadbook” exists” 

1st issue, every-time i will make the smallest change into the airtable base the zap will trigger but it will be stopped by the filter > +/- ok because i will have hundreds of filtered  zap runs...

Once i add the famous roadbook file (last step of my process), the zap will run and trigger the delay step until d-1 or d+1 for the SMSs.> seems OK BUT

1st issue : this method will trigger the zap at the very slightest change in the airtable entry (i work on it on a daily basis)

2 nd issue : once the PDF roadbook is present into airtable, everytime i will make a minor change inside airtable, the zap will run once again and the recipient will receive 2-3-4-5 or more SMSs

> Stuck

If I add an airtable button “OK SMS” or even if i create an airtable automation who says “trigger zapier at event day -1” the zap wil run again and again every time i will make a change in airtable...> Stuck

Do you have an idea to help me achieve my goal ?

Thank you !