I just mailed my I-751 packet to Nebraska Service Center a few days ago..they should receive it anytime..

My concern is, I plan to go back to Hong Kong for visit this May, how long does it usually take for them to mail me the notice to extend my green card for a year?(it expires April 25, 07)

The most important thing for me now is to get the notice on time so I can go back to HK and then come back after my green card expires.

See my timeline for your answer. I sent my I-751 to Nebraska last September.

Thanks..

Looks like they're pretty quick!

You must be kidding.