Change current process:
Read location > read product (inbounds product)
to a new process:
Read product (no inbound so far) > set or read quantity > read location (creates inbound)
When ASNs are long and quantities are high it is better lo locate the product in the ASN before asigning it to a location and before entering any unit
Not sure if this helps but we book all stock into an GI (offhand) location first. That way you can easily ratify any discrepancies before stock hits pick / bulk. Especially helpful if stock is on pre-order as as soon as it's in pick locations, it's picked and despatched so how can you verify a query in this instance. Yes we have to do additional transfers from GI to pick / bulk but it massively cuts down on errors.