This option was never there..If it was as such PRS booking public will not get tickets.You can book online any time except between 23:30 to 00:30 AM which is a schedule downtime all days once ARP bookings at 8 AM...
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Since 60 ARP opens today for Sep16th the availability can be seen but booking is allowed only from 8 am.ARP bookings open simultaneously both for online & PRS.