See the sample form at Timestamping responses - #3 by LN.
It might also be good to read https://docs.opendatakit.org/form-logic/#when-expressions-are-evaluated to understand how once() works.
See the sample form at Timestamping responses - #3 by LN.
It might also be good to read https://docs.opendatakit.org/form-logic/#when-expressions-are-evaluated to understand how once() works.