It doesn't matter where you are in a workflow; you're always at the right spot to implement preflighting. That may sound strange but it is basically true; regardless of what happens in the rest of the workflow, if you preflight you will be better off. The only possible reason you might have to skip preflight is when you are 100% sure that the files coming in will be perfect 100% of the time (and the same for the files you send out of course).
You do have to realize that you will have to go further to reap the full benefits of good quality control throughout a workflow. Implementing preflight in one spot will benefit the workflow, but not as much as when all of the players in the workflow get involved.
If we look at the case studies we've done on preflighting and quality control that is one of the most important conclusions and it always comes back: if at all possible involve all relevant players in the workflow. Don't limit it to your own company.
It sounds very altruistic and not very commercially oriented to go out and educate for example your creators and printers if you are a publisher... But in the end it's really not; it's the smartest thing you can do. A workflow that implements proper quality control will gain you so much in cost-savings and efficiency that it is well worth the initial effort.
The third part of the question for this article is the "How?" and there is no easy answer on that. Let me give you a couple of guidelines though.
First of all, you'll have to decide which preflight technology you want to use. Decide that by looking at the quality of the preflight engine and how user-friendly it is for your purpose. Also keep in mind that the preflight rules you want to use might make a difference in your choice as well; not all preflight engines out there support the same preflight rules.
The preflight technology you select probably exists in multiple forms, and they all have their purpose. So consider where you want to preflight and then check out your options. Let's look at a couple of possible ways you could use preflight software in your workflow.
PDF File Creation
A number of applications such as Agfa Apogee Create, Creo Synapse and Enfocus Instant PDF integrate the PDF file creation and preflight process. If you regularly have to create PDF files and then verify that they are all right before sending them off, this might be an ideal solution.
If you receive a small volume of PDF files, or regularly have to open PDF files in Adobe Acrobat, a plug-in preflight tool that works in Adobe Acrobat might be a better solution. pdfInspector2 from Callas Software is one solution; this is the same technology as included by default in Adobe Acrobat Professional 6. One other solution is Enfocus PitStop Professional, which does comprehensive preflighting but also allows users to fix the problems found (we'll talk more about fixing problems in the next piece).
If you have a larger volume of PDF files that need to be preflighted, you are probably better off with a solution that does not require Adobe Acrobat Professional but works standalone. Enfocus PitStop Server is one such hot folder based preflight tool, but almost all major workflow vendors (Agfa, Artwork Systems, Creo, Screen...) have their own workflow system that integrates preflight. Depending on what you are looking for in terms of price and feature set one of those might be your perfect solution...
I can't tell you which product to use -- as I work for Enfocus Software, that would not be fair. But there are reviews enough out there to give you an independent overview. And if you are in doubt, ask people on the prepress forums or even better, download trial versions and test for yourself.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.