Just by putting in the live rock you should be starting your cycle form the die off from the live rock. That will produce a certain amount of ammonia and you can go from there. Either adding a dead supermarket shrimp or dosing with pure ammonia will up your ammonia, I aim for 4ppm to start with. As your cycle progresses you should start to see the ammonia level drop and the nitrite levels rise. Keep dosing your ammonia though until your nitrites drop to 0 all by themselves. Thats probably the longest part in my opinion, waiting for the trites and then for them to go to 0.
If you are gonna add anymore rock when you start is the time to add it so it also can get the benefit of the bacteria base you will be building up. although 50lbs in a 29g is good pretty much in my opinion.