since nobody else will answer you, i'll try.
there is no advantage (or disadvantage) either way to not sending the articles, and nobody really knows for sure why she went this route. but i'll attempt some motive here.
when the house was presenting/voting, there was already chatter that the senate was going to kill it, quickly and quietly, likely before christmas, and that'll be that. at that point, mcconnell wanted it either dismissed, or at worst, quickly voted down. trump, on the other hand, was squawking about a long, drawn out trial (as were many other r's) that would go 6 days a week, all day every day for months, calling everyone and everything not nailed down as a witness. keep in mind, when i say "witness" i don't mean in the traditional sense, you know, someone who brings in actual facts relating to the charges. i'm talking about people they could call and smear and grandstand to, in hopes of screwing with biden's chance in the election (the only play in trump's playbook).
after some time, mcconnell convinced trump this was not the right move, and that he would handle it, and kill it dead. it was also around this point, when people like lindsey graham went on tv to announce they had no intention of being fair and impartial, and that they already had their mind made up.
so nancy had two choices - either send 'em on over or stand pat for a minute, and assess some options. with the holidays coming, she probably felt there was no hurry, and didn't want it buried in the news cycle, so she waited 2 days, and they went on recess. to me, there is no disadvantage to waiting a couple of days (which is a couple of weeks when you account for the holidays). it was her way of controlling the narrative so that people visiting with their families would be discussing the facts and merit of what the house brought forth. again, this is my speculation.
holding also isn't what the republicans were expecting, and it's always a good idea (for nancy) to keep them guessing, and she seems adept at doing this, with the added bonus of getting under trump's skin, something she does exceptionally well. and it worked, because he started in with the tweets, "if you're gonna impeach me, do it now, do it fast" and so forth. as for your question of why would the r's want it - they shouldn't want it, and shouldn't care, but since they know it's coming, they're kinda forced to address it.
so now the holidays are over, and she started demanding fair trial rules - something nobody thought she'd get. and she didn't. but it allowed for more time to stall, and lo and behold, news comes out that bolton will testify, if subpoenaed, by the senate. and even though the likelihood is small that we'll ever hear from him, it throws a bit of a monkey wrench into the senate r's plan of "we don't need to call witnesses". it also sorta makes holding look like a calculated move that could start to bring out more actual fact witnesses.
now, when she does send them over (which apparently is happening today or early next week), her argument over a "fair" trial with actual witnesses holds a little more water. and hopefully, people will notice a difference when mitch says "fuck off", than if he said it a month ago (which he basically did). personally, i think the longer you wait, the more chance trump has of going off the rails and reversing course back to the long and drawn out trial where he thinks hunter biden will come testify and it'll be a big win for him with ukraine aid.
tl; dr version - my opinion is that nancy did it to fuck with r's. we have no idea why, or if it'll work. there's no reason to go quickly if you already know the final decision. might as well wait and hope for some unforced errors.