To auto-enter the creation timestamp from the host, all you have to do is specify an auto-enter calculation on a Timestamp field referencing the Get(CurrentHostTimestamp) function. It's that simple. However, it's a little more difficult if you want to auto-enter the modification timestamp from the host because you want the timestamp to update when the user modifies any field on the record.

One solution is to use the Evaluate function. The Evaluate function calculates the first or expression parameter as if it were a formula. For instance, you could type a calculation formula into a field and feed the field to the expression parameter of the Evaluate function. However, it's the optional second parameter that's important in this scenario. The second parameter lets you specify one or more fields to trigger the Evaluate function to recalculate. So, you could specify all fields in your table as in the formula:

Evaluate(Quote(Get(CurrentHostTimestamp)); [Field1; Field2; Field3])

The Quote function is required because you're entering the value directly into the first parameter of the Evaluate function. Specifying a field reference wouldn't require the Quote function because FileMaker Pro already interprets it as text. When you type the formula directly into the expression parameter, you must enclose it in quotes for the Evaluate function to interpret as text rather than a formula.

The only problem with the above formula is the need to update it every time you add a field to your table. A better solution is to create a new time field (Time_Mod) that auto-enters the modification time. With this new field, the above formula changes to:

Evaluate(Quote(Get(CurrentHostTimestamp)); Time_Mod)

The Time_Mod field updates whenever users modify any field and triggers the auto-enter calculation on the timestamp to reevaluate. Don't forget to deselect the auto-enter option on the timestamp field to "do not replace existing value of field (if any)" so the auto-enter can overwrite the timestamp whenever a user modifies a record.