First, fermentation can take up to 72 hours for the yeasties to start, it's called lag time.
https://www.homebrewtalk.com/f39/fermentation-can-take-24-72-hrs-show-visible-signs-43635/
Secondly, what do you define as a "sign of fermentation?"? I don't see you mentioning a gravity reading, so I'm going to assume that you, like 99% of the other "My beer's not fermenting" thread starters, are going by airlock bubbling NOT a hydrometer reading.
Get out of the idea of using "airlock bubbling" as a sign of fermentation, you have to realize that airlock activity is not an accurate indication of fermentation...an airlock is a vent for excess co2, nothing more...and half of my beers never bubble.
Read this...
https://www.homebrewtalk.com/1217925-post3.html
The only way to truly know what is going on in your fermenter is with
your hydrometer. Like I said here in my blog, which I encourage you to read,
Think evaluation before action you sure as HELL wouldn't want a doctor to start cutting on you unless he used the proper diagnostic instuments like x-rays first, right? You wouldn't want him to just take a look in your eyes briefly and say "I'm cutting into your chest first thing in the morning." You would want them to use the right
diagnostic tools before the slice and dice, right? You'd cry malpractice, I would hope, if they didn't say they were sending you for an MRI and other things before going in.....