The Department of State publishes Visa Bulletin every month which will determine the allocation of available visa numbers to immigrants. For DV selectees, this number is based on their case numbers. Look at the link below:
http://travel.state.gov/visa/bulletin/bulletin_1360.html
For example, look at August 2010 VB under
"B. DIVERSITY IMMIGRANT (DV) CATEGORY" which will show you the allocation cut-off numbers for that month and advance notification for the following month. Visas are available only for applicants with DV regional lottery rank numbers
BELOW the specified allocation cut-off number as shown on the VB. For example, the allocated cut-off is 28,700 for Asia for the month of August, which means only those with case numbers below the cut-off number can apply as visas are only available to them at this time. It also shows advance notification for September which shows "CURRENT" for Asia which means, ANYONE can apply regardless of their case numbers, and this will be based on first-come first-served. As we are nearing the end of FY2010, it is not unusual to see "CURRENT" for all areas as all 50,000 visas must be issued by September 30, 2010. The VB usually comes out around every 15th of the month. August 2010 VB just came out yesterday. You may want to refer to older VBs to get a gist of when you can expect to become current for FY2011.
You don't necessarily have to wait for your number to become current to prepare for your AOS. You can start the process whenever you want with the exception of Medical Examination (which is valid for only 12 months) and most people do it around the time they become current. But you can start collecting all other documents now. But you can only send the complete AOS package when your number becomes current. There is a lot of debate about sending in the AOS package in advance. It is not really written in stone but some 2009 and 2010 folks with high CN and current around the end of FY have sent in 50 days in advance (for example if you are current in August, you will know so around June 15th with the advance notification for August which will give you about 45-50 days) and these folks have been fine. As, I stated earlier, this is not written in stone and is just my observation.
On the same note, FY2011 has to start for you to send in your AOS package, those with low CNs and expecting to become current in October 2010 can only send in their AOS packages on and after October 1, 2010 as this is when FY2011 officially starts.
I received my receipt for the $375 that I sent. I will send out the $65 difference today or tomorrow.
I do not understand when people say "when your number becomes current". What does that mean? Where do i check if I am current? Is there a site?
Also, what are my next steps? Preparing and making my i-485 and supporting docs ready to send to Lockbox? But i can't do that until my number is current right?