When will I be eligible to apply for US citizenship if my husband and I don't live together?

I got married to a US citizen in 2008. I got my green card in April 2012. I didn't apply for green card before April 2012 as I was on J1 Visa. From 2008 Dec-2010, we lived together. However, because my husband had a tough time finding job in the state I work in, he moved to different state where he found a job. I remained with the same job as I had to complete my project with my present institute. We also have a baby who is one year old now. At present, I can move as I have completed my project. However I am not able to move to the same state as my husband as I am not able to find a job. We meet every weekend and my husband spend two months every summer with us. My first question is, can I apply for citizenship after 3 years or do I have to wait for five years if we stay in two different state? My second question is, if we start living together in the next few months, when can I apply? Being a citizen will open a few more job opportunities for me which in turn might help us stay together as a family. I would appreciate any suggestions.