In the next week or so, I need to add 20K miles from another one of my mileage programs to United MP (Premier Gold if that matters).

I have surplus Amtrak Guest Rewards, and since I am Select I can transfer up to 50K/year out. Webflyer calculates that the best way to transfer from Amtrak to UA is via Choice Preferred. According to Webflyer, AGR converts to Choice at a ratio of 1:3. That is, 1 Amtrak = 3 Choice. I see the same 1:3 exchange ratio on the Choice Privileges web page this morning. While there is still a 5:1 reduction in the second step conversion from Choice to UA Mileage Plus, the initial tripling makes it a pretty good deal overall.

The only snag is that Choice web site cautions to expect to wait 6-8 weeks to clear through Choice, and I need to make the transfer faster than that.

I would be happy to pay a reasonable fee for expediting the transfer if Amtrak/Choice had a service like Marriott's fee for expedited transfer, but I can't seem to track anything like this down.

Does anyone have experience on the ground on how long the transfer from Amtrak-Choice actually takes, and then how long before I can transfer the new Choice points to UA Mileage Plus?