It's less about the time of day and more about the rarity.
In many places Charcadet spawn, it has a 1% chance to spawn, making it quite the rare spawn. Luckily, there are easy ways to find it.
SANDWICHES!!!
If you're playing early in the game, you can make a Pickle Sandwich to get Fire Encounter Power 1, with Pickles available at Sure Cans and Olive Oil available at Artisan Bakery, both near the West Pokemon Center in Mesagoza. If course, if you're later in the game, you can make better sandwiches for more Fire type spawns.
There are also a couple guaranteed Charcadet across the maps, such as in South Province Area 3 and West Province Area 1, if you want to grab those instead.
Also, if you're worried about actually catching it, it's catch rate is only 90 (11.8% with a Poke Ball), so you should be able to easily catch it after weakening it. Although using a Dusk Ball at night does provide a higher catch rate.
Hope I helped!