It would help to know the particular colleges you are referring to because there are differences but most colleges, including those with early Jan application deadlines, accept for regular admission through the Dec SAT and ACT test dates or the Jan SAT test date, and most of those with Dec test date as last one accepted want any scores in their hands by about mid-Jan and those that accept the Jan test want any scores by no later than right after scores are released in Feb for the Jan test. There are exceptions that want scores earlier for regular admission and some that even take the Feb ACT test. Also, if you have applied early action or early decision, for which admission decisions will be released mid-Dec, you really should have sent your scores already except some of those accept Nov test scores and thus you have a little more time because those scores don't even come out until next week.
As to how scores get sent:
SATs: most if not all colleges now have electronic delivery which means each has an on-line account with College Board into which CB places any scores ordered sent to the college. If you designate colleges in a test application to receive scores upon release, they are usually put into that on-line account about two business days before the test scores are released to the test-takers on-line unless the college has requested specific other times for dumping into its file (like only once a week). If you order scores sent after test scores are released, then the scores will be placed into that account within a few days to a week or more depending on when order is made. If order is made right after a test score is released the time is usually the longer because tens of thousands of test-takers are submitting orders at that time and despite electronic delivery, human beings still need to process and verify those orders and CB has only a limited number of human beings to do that. If you order rush delivery after a score comes out, you may shorten the period it takes to get the score into the college's account by a few days.
ACT: like CB, most have electronic delivery and on-line accounts with ACT. If you designate colleges in a test application to receive scores upon reslease, ACT will place the score in the college's account when a day or two after score is released but not until after writing score is released. If you take ACT with writing, it is very common for only some of the test-takers to get their writing score on the day test scores are released and the writing scores for others are released over the next few days to a week. Thus, nothing is sent until that writing score is available. If you are ordering tests for which you already have scores, it can take a few days to a week or a little longer to get the test into the college's account depending on when the order is made (like SAT the process is longer right after test scores come out when tens of thousands order their scores sent).
Getting the scores into the college's account is only stage one of the process. The college then has to go into that account and download scores (some do it daily, some weekly, some biweekly) The college then has to match the score to the applicant's admission file which can take anywhere from a couple days to two weeks depending on college.
My recommendation is that if she already has the scores to send and knows to which colleges to send them, she just do the orders now. You can send scores before you submit application for admission -- college will start your admission file and match app to it when it comes in.