By referring to Ecam CG, GWCG (generated by FCMC), Seagul1 was considering A330/340 procedure.
A320 skippers, you don't have a CG displayed on Ecam (read the question
)
>2% difference is the value that will trigger a sorough re-check of your ZFW and ZFWCG, you rely on Ecam CG in any case (given you did a proper re-check).
In any case you set your THS according to ECAM.
On A330-200, you can accurately set your THS easily without referring to your QRH:
ex.:
If ECAM CG
before pushback is 28%, first THS is always nose up:
THS is
(35-GWCG)/2 = (35-28)/2 = 3.5UP easy
(why? because by design, THS is a linear application of TO CG)