If you are looking for some type of notification on dates / time then have a look at my 
Calendar Notifications & Actions blueprint. Try and set up a calendar for service ( I have one for home and one for service) then put in you calendar events in service when you change the filter + 90 day and then it will notify you when to do it 
No need for input number. In this blueprint it can work of a key word or not. That is why it so good to set up a calendar for service and dont use key word, then every event you put into service you will get notified. One blueprint, one automation covers every service item. Just use the the title and description sensors built in so you know what your being notified of. Example
- Ice machine filter
- Fridge filter
- Bins rubbish reminder
- Fertilise lawn
- Clean gutters
- Check pool
- Clean range hood filters
- Change oil in lawnmower
- Service XYZ
- etc
Or you can use key word and have a custom automation tailored to your event 
Blacky 