what is a safe period to return to US before the H1B visa/ stamping

[Immegration-Help]

Hi all,
My H1B visa stamping is till Dec 31st 2019. I am planning to travel during the last week of November and return to US on Dec 2nd 2019. And will file for H1B extension once I am back.
We all must have been in a similar situation in the past, could anyone share her/his experience? And based on your experience what is a safe period to return to US before the visa/ stamping expires?

Thanks in advance for your suggestions and advise,

[gopalakrishnach]

I guess you are good and tell same reason at immigration.