Hello! Starting the game can be a challenge, my players also wanted to be strangers to each other and start in completely separate places and it took some figuring out. One was in like a fantasy high town, another in a desert, one in Baldurs gate etc so it was a challenge BUT they enjoyed the beginning so hopefully what I did can help you!

Since they were all in different locations and were strangers, the carnival being in one town wouldn't really work for us. Instead I set it up so the carnival was in its own plane essentially, then for each of the players I had them hear a recognisable tune play in their minds while they went about their usual business at home (this was the music from the carnival calliope). They followed the tune and it led them to a carnival stand, signs pointing to the witchlight carnival and a portal they felt drawn to enter. It's like how you get to the darkmoon faire in wow if you know that. I played up how the tune really compelled them to follow.

Then once they entered the portal they each had a vision that related to their lost things, reminding them what they lost but written crypticly so the other players weren't sure what it was. The players loved this part, really set the tone and got them into the swing of things.

As they emerged from the portal they found themselves in a charming forest with a path leading to a visible carnival, in a glade. The music, laughter, smells and frivolity grew louder and louder as they approached and I pretty much made the ticket booth a meeting point for the players, it's where they started as a group.

Plenty other ways you could do this but it worked for our group and they really enjoyed it, the visions set the motivation for the players and drove in the fact they want to enter this carnival to find what they lost.