You could use AutoNumber, append in enough dummy records to get up to one
less than the number where you want it to start, then delete the dummy
records. Just don't do a compact/repair until after a valid new record is
entered. The AutoNumber does not get reset back to zero unless a
compact/repair is done whil the table is empty.
Alternatively:
Instead of using AutoNumber in the table, set the data type as Long Integer
and do something like this on your form:
Set the default value of that field (let's call it CustomerID, from the
Customers table) to:
=IIf (DCount ("[CustomerID]","[Customers]")=0, <Enter your starting number
here>,DMax("[CustomerID]","[Customers]")+1)
This will assign the starting number to the first customer entered and
increment from there onward. This is not quite like AutoNumber in that if one
user opens the form while another user has an unsaved record open on the
form, they will both get the same number - a perennial database problem. You
can alleviate this by checking to see if the number already exists right
before you save the record (Form_BeforeUpdate) and incrementing it again
until it comes up with an unused number. This will be a moot point if this is
a single-user application.