It is possible to iterate through the database objects (in your case, table container) to find a particular one. So there's the rub - will it always have the same name? If not, something about your form has to allow the user to, or cause the table to, be identified. If it's a user action, it could be based on some combo box selection for example.
As for a green check, a checkbox does not have a background colour property AFAIK, but you can put a rectangle behind it, which you'd colour green. Or you can change the attached label for the checkbox to say LOADED if you wish. All of this would require a procedure on the form. If you intend to use this on more than one form, it would be better to put the code in a standard module so that all forms that need it can access it.
To go any further, you'd have to tell us/me how to identify the table that is the subject table. This forum does not allow you to upload a copy of your db, so you'd have to be able to post relevant code that exists behind the form. You also asked for pointers, so try searching for 'MS Access loop table def' . Here is some air code that you could use in a function to return True or False (TRUE = table has been imported; FALSE = has not been imported). Note: no error handling supplied at this point
Code:
Function TableExists() as Boolean 'table name as parameter in brackets if this is a volatile parameter
Dim db As DAO.Database
Dim tdf As DAO.TableDef
TableExists = False
Set db = CurrentDb
For Each tdf In db.TableDefs
If tdf.Name = "nameOfSubjectTable" Then
TableExists = True
Exit Function
End If
Next
End Function
Whatever calls this function gets either True or False as a result, so the checkbox is set to True or False accordingly.