In it, but not of it. TPM DC
The delay between election day and certification of the winner is provided for by state law in order for local election officials -- there are 351 local election offices in the state -- to certify their totals, and to count overseas absentee ballots that have not arrived until after election day. The deadline for absentee ballots sent from overseas to reach their local election offices is 5 p.m. on January 29.
Tassinari also explained to us that January 29 is not necessarily the endpoint. Ballots must arrive by 5 p.m. on that day, and the local election officials cannot have their meeting to count them until after 5 p.m. that day. The local election officials then have up to five more days to resolve any provisional ballots before they certify their local election results, which must be done by February 3rd.
After the results are received from the local election officials, the Secretary of State will present the total results to the governor and the Governor's Council for certification. Only after the results are certified by the governor and the Governor's Council can a certificate of election be issued. (The governor and the council schedule their own meetings, which usually take place on Wednesdays.)
So what does this all mean? Looking over these statutes, it seems clear that unless the result is very, very close (think Al Franken and Norm Coleman in Minnesota, or Scott Murphy and Jim Tedisco in NY-20), we should probably know on election night who has been elected when the vast majority of votes are counted. But even then, state law is clear that a certificate of election cannot be issued until at least 15 days later.
And if Senate Democrats insist on a completed certificate -- just as the Senate Dems did in their unsuccessful attempts to keep out Sen. Roland Burris (D-IL), and Senate Republicans did in their successful blocking of Al Franken during the Minnesota litigation -- that would keep the winner out for at least 15 days.