This is way too dependant on the campaign
Every DM runs a different sort of campaign and has different expectations of what the game should play like. So the advice that every one here gives is going to be influenced a great deal on what their games are like.
For myself, games that I run are set up in such a way that the player characters are usually not integral to the plot arc of the campaign. I set up the world and set up some dire scenario that the PC's can intervene in, but the PC's usually do not have a personal attachment to the story. This changes later in the campaign based on in game events, but early on the PC's are not individually important to the story. I am trying to play a game, not recreate the Lord of the Rings in the 'make beleif with dice' medium.
This is because Fecal Matter Happens. Players that thought they could play regularly turn out to be unable to. Or they realize they hate their character and want to play something else.
This means that in my games, I basically hand the players the PHB and let them go to town. I ask them not to make evil characters, but that is about it. My initial story hooks are in no way dependant on specific character types being available.
If I want some back story, I will wait until I know what kind of character the PC is, and then invent something consistent. But the hooks I create are also not important to the inital adventure hooks. I might use them later, or I might work the hooks in as an opportunity arises, but that is it.
Now, if you have an urge to run a campaign where the heroes are personally invested in the campaign and everything that happens is part of some intricate story you have been thinking of for months, this might not work. Perhaps Monks just dont fit in your campaign world, and becuase the story centers on an Elf king summoning heroes to oppose a demon army, the thought of said Elf king appointing a half orc barbarian as a Defender of the Realm just shatters the aesthetic qualities of the story.
And now my advice regarding pre campaign handouts.
If your hoping to run a game that has a strong narrative element, you need to sit down with your players, tell them roughly what the campaign will be about. Tell them about the kinds of things you prefer not to see. List all the class and race restrictions, and tell them about the campaign setting. Most importantly, make sure they actually want to play in that kind of a game. If you dont want someone to roleplay a Gnomish Bard who thinks he is a ladies man who takes his ques from Leisure Suit Larry, you will want to spell that out early.
If your just hoping to collect a handfull of character hooks that you can use to let your players justify going on an adventure, then your probably best off letting the players create what they want, and creating the hooks after you know what your players are looking to do.
Lastly, If you intend to have any sort of character backstories created in advance of the campaign, then you will absolutely need to have all characters created well in advance of the first game. This means you will probably have to use a big chunk of your first game just creating the characters.
If you want your players to be able to show up to the first game ready to play with fully statted out characters in hand, your best off forgetting about having any character hooks created before the game. You will be lucky if you can invent a plausible reason for the players to work together.
Bonus: General purpose excuses for the players to work together.
- If all are same race, or can otherwise be made plausible, go for siblings or childhood friends.
- Start the game with all the players in jail as cell mates.
- Start the game in an Inn and have an Orc Raid attack the town
- Declare all characters as orphans in the same orphanage.
- Start the game on a sinking ship.
END COMMUNICATION