Lightroom
Library tab
Grid mode
Metadata
sort by camera serial number (that is if you have 2 same bodies)
select camera - highlight all the photos from that camera
Right hand side, scroll down to Metadata - captured time - click
You can change it there, but tbh, the hardest part is get it timed 100% correctly.....
I actually did this in a wedding knowing one of mine was 15 seconds out. I saw a clock, a camera each in hand, photographed the clock at the same time. When i got home i compared the time stamp with the clock's Second Hand.