Let's unpack this a little bit:

[quote=@NuttsnBolts]
Have any of you noticed that it is often several days or even a week or so later until a roleplay truly starts?
[/quote]

There's no hard, fixed, rule about the thing. If I'm doing a RP in Casual that doesn't require a lot of "groundwork" it can go from Interest Check to OOC post to IC post in a relatively short amount of time. Say three days. 

If I'm doing an Advanced game with complex histories involved in the Character Sheets, and Character Sheets themselves that involve multiple characters, than it could all take quite a bit longer to go from Interest Check to OOC post to IC post. Weeks aren't out of the question. During this time there's usually OOC chatter going on, either in the OOC thread, or in the game chat, so while there isn't an IC kickoff or lots of Character Sheets getting posted, there's still a fair amount going on.

So long as you don't lose your group of RPers, I think you're okay. Push too hard, or wait too long, and yeah--you run into issues as a GM.

[quote=@NuttsnBolts]
So the thought crossed my mind, but do some people space out the process of starting a roleplay to a length that is too long? 
[/quote]

Yes. It's probably not terribly difficult to find examples of this.

[quote=@NuttsnBolts]
Could, or more should, a GM place a character sheet template in the Interest Check so people can start working on their characters sooner?
[/quote]

Could they? Sure. Sometimes they do, sometimes I have. Should they? If they'd like to, sure. If they don't want to, if they want people to wait until the OOC is up, that's fair enough. Really depends on how complicated a character sheet it's going to be and how long a wait until the OOC goes up. 

[quote=@NuttsnBolts]
And how much should a GM prepare their own works (OOC, Characters, and IC #1) before choosing to start their roleplay?
[/quote]

Depends on what you mean by "start their RP." If you mean, by the time you throw up an Interest Check, probably not. (Again it's up to everyone's own preferences.) What if you don't get enough interest? What if your OOC needs to change because of questions/issues brought about during the IntCheck phase? Ditto the first IC post: what if you need to know what characters you have so you can include them?

It's a good idea to have a solid foundation and good grasp on your game before throwing up an IntCheck, unless you're just usually good at winging it. Otherwise, you want to have some idea what you're doing I think. But do you need your OOC finished before your IntCheck? Probably not. Should you do an IC post before an OOC or IntCheck? You may not want to, for a few reasons. 

But, afterall, GMing is a rather personal thing. Each person has their own methods, each person has their own preferences, and so long as they can make it work, that's all that really matters. If it's not working out for them, you'd hope they either reevaluate, or just stick to being a RPer and not a GM.