online assessment centre preparation

Hi Forum, first timer here and hope get response. I have applied for Asylum Decision Maker job and its been almost a month receiving the email saying ,,,,,
We are pleased to inform you that having carefully reviewed your results, we will be progressing your application further.

We are currently arranging the online assessment centre schedule and will be offering spaces on a merit basis.

You will be invited to select a suitable date and time shortly or alternatively be placed on a merit list for the next available spaces.
My question is: what sort of time it could take and also for the online assesment what kind of preparation to take? is it quite hard?
TIA

Not hard at all mate just have few examples of each competency and you will be fine create your answers by following the success profiles Civil service behaviours (easily available in google) at the grade you have applied for and to be definitely sure u nail it I'd recommend even preparing your answers for a grade higher as that way there's every chance you'll well exceed the required standard.
In regards to the time frame things always start happening after advert closing date nd bare in mind civil service isn't the fastest nd is definitely a lot slower then any private sector recruitment you gotta be patient