I've was lucky enough to buy from Martin on two of his previous sales.
On the last two shipments it took about a week from when I got the notification to the first attempted delivery by USPS. Since it's international it's Registered, which requires a signature for delivery, so I actually got them on the Saturdays following delivery since I work and no one is home during the day to sign.
I live in Southern California.
So if you live on the West Coast, and you have someone to sign, you could potentially see the caps in about 7 days.
Also, make sure you track it with USPS's site as well since once it lands in the US, USPS uses the same tracking number to deliver to you.