Wait until a file exists before continuing?

Trying to write a bit of a big script that will wait until Distiller finishes making a PDF before proceeding with opening the PDF into PhotoShop. Is there a repeat loop I can put in or some other syntax to do this? I am figuring a “repeat while not exists” loop or something like that, but I thought I would see if any of you know anything fancy.

OS 10.3.9.

Thanks.

Model: Mac G5
Operating System: Mac OS X (10.3.9)

I have seen this done by having finder do a repeat loop watching the PDF’s file size increases when they reach a constant the file is then passed on. I “think!!” I saw this in Quark’s forums for watching postscript files before passing on to Acrobat for people without the Pro version.
Here is some syntax for photoshop if you don’t already have some might be of use:

set tempFolderName to "Converted to CMYK TIF at 300dpi"
set inputFolder to choose folder

tell application "Finder"
	set filesList to files in inputFolder
	if (not (exists folder ((inputFolder as string) & tempFolderName))) then
		set outputFolder to make new folder at inputFolder with properties {name:tempFolderName}
	else
		set outputFolder to folder ((inputFolder as string) & tempFolderName)
	end if
end tell

tell application "Adobe Photoshop CS"
	set display dialogs to never
	close every document saving no
end tell

repeat with aFile in filesList
	
	set fileIndex to 0
	
	tell application "Finder"
		set theFile to aFile as alias
		set theFileName to name of theFile
	end tell
	
	tell application "Adobe Photoshop CS"
		
		set ruler units of settings to cm units -- to be used for the canvas resize, remove if NOT required.
		
		set background color to {class:RGB color, red:255, green:255, blue:255}
		
		open theFile as PDF with options {class:PDF open options, mode:CMYK, resolution:300, use antialias:true, constrain proportions:true}
		
		set docRef to the current document
		
		tell the current document
			
			set docHeight to height of docRef -- to be used for the canvas resize, remove if NOT required.
			set docWidth to width of docRef -- to be used for the canvas resize, remove if NOT required.
			flatten
			-- this line below cuts OFF the 1cm to all edges around my print PDF's
			-- removing bleed and registration marks, remove if NOT required.
			resize canvas width (docWidth - 2) height (docHeight - 2)
			
			set docName to name of docRef
			set docBaseName to getBaseName(docName) of me
			set newFileName to (outputFolder as string) & docBaseName
		end tell
		
		save docRef in file newFileName as TIFF with options {byte order:Mac OS, embed color profile:false, image compression:LZW, save alpha channels:false, save layers:false} appending lowercase extension with copying
		close current document without saving
	end tell
end repeat


-- Returns the document name without extension (if present)
on getBaseName(fName)
	set baseName to fName
	repeat with idx from 1 to (length of fName)
		if (item idx of fName = ".") then
			set baseName to (items 1 thru (idx - 1) of fName) as string
			exit repeat
		end if
	end repeat
	return baseName
end getBaseName