fixation

Can you please explain fixation if scales are upgraded and someone like me is working at basic of 8900 in the scale of 6500 on 1.1.06 after IACP and promoted on 27.04.06 in the same scale and fixed at 9700 on 1.10.06(month of increment and promotional benefit)In oct 2007 upgraded to scale of 7500 after II ACP and fixed at 10000 in the scale of 7500-12000.Now these scales are upgraded.How my pay will be fixed and when should I give my option for fixation for maximum benefit?