Just a few facts, I hope it gives you a bit more insight.
Some deliveries come direct from the manufacturer, air freight from the far east or from the manufacturer's distribution hub (usually in the Netherlands). This stock is shared out (allocated) at this stage by the manufacturer and they communicate that to us at that time...it's usually about a week then before it arrives.
Some deliveries come through the distributors (Asus always this way). They'll send all of the UK's stock to their distributors and then tell the distributors who to sell it to, at which time the distributor communicates that to us....it's usually then arrives at our door next day...so you can see how little notice we'd have in this situation.
Right now, thanks to the pile up of issues at customs, transportation delays and admittedly, delays within our goods in department, accurate ETAs are very hard to give, even for stock that is sat at a local distributor. For example, I know that a MSI delivery was schedule to land at Manchester airport on Monday but it still hadn't arrived at the distributors when I checked yesterday. I won't know exactly what we are getting until the distributors have received and inspected their delivery and cross checked that with the allocations from the MSI product manager.
With regards the disappointing "ramp up". We can only communicate what we were told, we weren't ever given specifics about how many cards would be available. Nvidia communicated that GPU supply would ramp up significantly but I also believe that Nvidia yesterday(?) also communicated that GPU & memory supply wasn't the problem(?) So, the fact that supply hasn't picked up as much as we assumed is unfortunate and frustrating, (and yes, I admit we made an assumption based on the verbal communication and we've been left red-faced because of it) but there's no sinister hidden story. My best guess is that certain components shortages are to blame (similar to the capacitor shortage earlier in the year) but manufacturers are tight lipped.