I got all the generic common app confirmations but so far 1 school sent an individual letter with portal login etc. how long does it usually take ?
Portals often need to be manually set up (or at least part of the process is manual). If you submitted your applications over winter break, the admissions office staff may not have gotten back to set them up. Even if the offices were technically open over the break, they were almost certainly working at reduced staffing levels and portal setups are probably one of the tasks being deferred.