You can both send them anything anytime, as long as the package is specified with the file number it belongs to. What I would suggest though, sponsor should send everything to the applicant add the additional proofs and more evidence to the package and then applicant sends the package to CHC-Islamabad.
After providing documents, there is no time limit, one 2 ka 4 sent everything requested and his wife's file in now sitting in the interview que he applied towards the end of 2009, and I know a few member who applied in early 2010, received these objections by the end of 2010 and got VISAs by Mar/Apr 2011 so it really depends how strong your package looks and also a little bit on your luck as well. If they are convinced with what you have provided, it goes faster, if not then the wait is longer...