when exactly do big 4 recruit trainees ?

[bil_zahid]

i am asking this question because when i contacted these firms, they told me to come for 'trainee application forms' in the 2nd week of March 2010.

however i hear every now and then someone 'getting a call' from a big 4 firm and also about people applying there at other times.

so what the hell is this. if they only start their 'formal' trainee recruitment process every 6 months then.

also id like to know if they have separate recruitment/trainee programs for ICAP and ACCA students which might be causing my confusion.