here's my .csirc:

(system "sleep 1")
(use parley)
(parley-debug #t)
(let ((old (current-input-port)))
     (current-input-port (make-parley-port old)))

I've put some extra debugging in parley.scm (I will put that in an annotation):

If I start csi and then start typing "abcdefgh" while it's still sleeping, I see the likes of:

alaric@ubuntu:~$ csi

CHICKEN
(c)2008-2011 The Chicken Team
(c)2000-2007 Felix L. Winkelmann
Version 4.7.0.3-st 
linux-unix-gnu-x86-64 [ 64bit manyargs dload ptables ]
compiled 2011-10-11 on ubuntu (Linux)

; loading ./.csirc ...
abcde; loading /usr/local/lib/chicken/6/parley.import.so ...
; loading /usr/local/lib/chicken/6/chicken.import.so ...
; loading /usr/local/lib/chicken/6/scheme.import.so ...
; loading /usr/local/lib/chicken/6/data-structures.import.so ...
; loading /usr/local/lib/chicken/6/extras.import.so ...
; loading /usr/local/lib/chicken/6/ports.import.so ...
; loading /usr/local/lib/chicken/6/posix.import.so ...
; loading /usr/local/lib/chicken/6/srfi-1.import.so ...
; loading /usr/local/lib/chicken/6/srfi-13.import.so ...
; loading /usr/local/lib/chicken/6/srfi-18.import.so ...
; loading /usr/local/lib/chicken/6/stty.import.so ...
; loading /usr/local/lib/chicken/6/srfi-69.import.so ...
; loading /usr/local/lib/chicken/6/foreign.import.so ...
; loading /usr/local/lib/chicken/6/foreigners.import.so ...
; loading /usr/local/lib/chicken/6/parley.so ...
; loading /usr/local/lib/chicken/6/stty.so ...
prev input: (#\a #\b #\c #\d #\e)
loop: ()
Entering read-raw
#;1> abcde
Read raw: "abcde"
loop: ("abcde")
So far: '("abcde")' '"abcde"' '"abcde"'

Error: unbound variable: abcde
prev input: (#\f)
loop: ()
Entering read-raw
#;1> f
Read raw: "f"
loop: ("f")
So far: '("f")' '"f"' '"f"'

Error: unbound variable: f
prev input: (#\g)
loop: ()
Entering read-raw
#;1> g
Read raw: "g"
loop: ("g")
So far: '("g")' '"g"' '"g"'

Error: unbound variable: g
prev input: (#\h)
loop: ()
Entering read-raw
#;1> h