Time of temp help

Hi!

This is my first month charting bbt. Only CD3. I have an alarm set for 6:20 each morning to take my temperature. My toddler woke up early today so I had to take my temp at 5:30. How much can taking your temp an hour difference affect your bbt chart? I’m wondering if I should just continue to keep my alarm for 6:20 and just take it earlier on days my toddler wakes up earlier or if I should now change my alarm to earlier in the morning (5:00).

Thank you!