You can use the select_change event on your sheet capture when a differenet
cell has been selected. Keeping track of prior cell entries can be tracked
with a phantom sheet to store prior values, if the prior value was null, then
you can send the following command

activecell.value = now

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"PM" wrote:

I have a s/sheet that needs to automatically have the system time inserted in
a cell if the previous cell is blank. I have tried several things and have
not had any joy.

Any help offered would be welcome.