With our tool below, you can look up the entry for your Ig. 96/11 in the W+F delivery records. Note that this is specifically for the conversion number, stamped onto the comb of the stock. As Ig. 96/11s retained their original pre-conversion serial number, you can look up the records for when the rifle was first delivered as an Ig. 89/96 on the page for that model, which you can find here.
NB: If an Ig. 96/11's stock was broken in service, it would sometimes be replaced with an Ig. 11-style example. In these cases, the conversion number was sadly not always restamped, and sadly there is no way to determine exactly when such rifles were converted.