I will recommend to apply nomination and RCB altogether, if you got proof of advertisement and other required stuff, it will come through positive. As nomination takes 6 months or more so doesn't matter whatever time your RCB takes, atleast you will be in the queue for nomination. Secondly, nomination doesn't have any fee. If we are hiring a migration agent, he/she should be capable enough to tell the rough idea about the outcome before hand as they do this on daily basis and they charge a fortune too.