I think it's really dependent on the firm. I've known paralegals who went to law school and came back as associates but they went to top schools so would've been in the running in any event (although they were also given 1L summer spots which they probably would not have got had they not worked as paralegals prior). One of my friends works at a big firm with a branch in SF where he says they indicated to him a willingness to hire someone they thought was impressive paralegal wise who was in a night program. I think in determining whether a "big firm" would be willing you'd have to look at the qualifications of the attys. there. If they are all Harvard, Yale, Stanford, etc. people then the odds of getting hired there are unlikely if coming from a night program regardless of whether or not you're a paralegal there. If the background is more like Santa Clara, USF, etc. and the attys. you talk to there don't really seem focused on law school then I think you'd have a very good shot at getting hired there if they liked you as a paralegal. I'm not sure if this is helpful or not.