H1b petition has to be sub-mitted by your employer by mail. Local office won't help you.
You can start to prepare your documents now. For example, talk with HR first. They need time to process your LCA for two weeks. Then they will sub-mit your case right within the 6 months eligible filing period.
You can also start to think about filing Eb2 after you sub-mit H1 petition. Labor certificate (LC) takes much longer time before 140 sub-mission.