Start Immediately!
There are very few good reasons to delay the start of your green card process! You should have started 2 years ago. Perhaps the only reason you might have waited is if you\'re counting on experience from your current H-1B position, then plan to move to a new employer / position using that experience as basis for your employment preference category (e.g. EB-2 vs. EB-3).
You have many steps ahead of you, and you may face uncertain delays during ANY of them. Who can predict how long the DOL, INS, or DOS will take to do their respective tasks in 1, 2 or 3 years? It might improve, or it might just as likely take longer. Before you know it you\'ll have run out of time on your H-1B status and then will have to scramble. Take a look at the posting of others who have run out of time and have had to take steps like move to Canada.
GET MOVING!