Time doesn't matter so much, although I've always had better luck at night. Two best places in my experience are Harmonica Town at the far end of the beach behind the fishery, between the rocks and the cliff, with a charge of 4-5, and Toucan Island on the little point at the end of the beach past the penguin turnout with a charge of 5.
--- 'Survival is key to your mission, Snake!' '......?'
I found like 3 old rubber boots when fishing in the stream at my farm, just south of the watermill. No charge, with a gold fishing rod and skill of 3. --- http://www.youtube.com/user/yunakitty - My youTube channel with Let's Plays! Currently playing Animal Parade.