I want to use a file after its been copied completely

Is there a way to automate a file to be dropped on a Compressor Droplet once its been fully copied over a network or finnished captured from Final Cut Pro?

Not too clear from your statement what you want to do, but the following AppleScript handler will not return until a copy is complete:

to IsSizeStable(myFile) -- can be a folder too
	-- initialize the loop
	set Size_1 to 0
	set Size_2 to 1
	-- repeat until sizes match
	repeat while Size_2 ≠ Size_1 --  loop until they're equal
		set Size_1 to Size_2 -- new base size
		do shell script "sleep 3" --wait three seconds, or whatever
		set Size_2 to size of (info for myFile) -- get a newer size
	end repeat -- once the sizes match, the download is done
end IsSizeStable

All it does is loop until two successive measures of file size match, then drops out and returns.