Okay, you probably know by now I'm a bit of a research nut. Even more so now that I have lots of computer time on my hands! lol
Apparently there are 3 major gestational milestones for women (like myself now) at risk of preterm labor/birth (PTL / PTB):
24 weeks - Baby(s) are potentially viable. But likely to have long-term issues. I was past this point when my cervix issues were discovered.
28 weeks - Baby(s) lungs can be made relatively mature with steroid shots, if labor is thought to be imminent. However, there are still some risks of long-term issues.
32 weeks - Baby(s) almost fully developed. Would still need steroid shots before delivery for lung development. But there is a 95% chance of survival, and risks of long-term complications are reduced. However, some weeks in the NICU would still be required.
(In my case, 32 weeks would be Feb 14 - Valentine's Day. 
Cute! Although I'd want them baking even longer! lol)
So I am at 28 weeks today (yay!) and so far have had no signs of PTL. I can say my Braxton-Hicks contractions *have* been reduced while on bedrest (BR), but they still do occur sometimes (and are more uncomfortable now than before, not sure why). When they occur, I try to rehydrate with water, and sometimes also use a heating pad on low heat to relax my uterus and stomach muscles.
However, I won't know what my cervix is actually doing until my next transvaginal ultrasound (TVU). I see my OB in a few days and will ask her for one then. I will also ask her for a fFN test (fetal fibronectin test). This is a non-invasive cervical swab test that can help predict if a woman is likely or not to go into labor within the next 7-14 days.
BTW, my cervical issues were actually diagnosed by an on-call OB two weeks ago, and I have not even spoken to my regular OB at all yet! Bah, public heathcare!!! So almost everything I have learned (and to do / avoid) so far has been based on my own research and initiative. My OB only works a few half-days per week and early on when I asked her what to do in an emergency, she told me to contact the hospital's Birthing Center. Niiice!!!! lol So, as usual, I don't expect or receive much guidance from the physicians I am dealing with. Fun!!! Yes, I have issues. lol <end rant>
Anyways, I've found some new support groups on BBC - one for women on bedrest and one for women with cervical issues. I've also found a ton of medical studies about cervical length and/or funneling and the associated risks of PTL, etc. However, most of those studies were done on singleton pregnancies, which are not always directly applicable to multi-fetal pregnancies.
Here is by far my favorite medical article so far regarding cervical changes. It's recent, and I found it very educational. It contains some great supporting graphs and tables. See especially Figure 2 (I believe my funnel was last a "Y" - apparently second best of four stages) and also Figures 4 and 5 for proposed management plans for patients like me. I am going to discuss these plans with my OB next meeting. Essentially, I believe I should be having fFN tests + transvaginal ultrasound checks of my cervix every 2 weeks. Let's see what she says! lol
In summary, based on what I've found so far, I believe my cervix issues put me at a 30-50% chance of delivering before 35 weeks. But that could be any time between now and then (7 weeks!). Let's see.
BTW, there is thought to be some linkage between subchorionic hematomas (SCH), which I had in the first trimester, and an increased risk of PPROM (preterm premature rupture of the membranes) and PTL (preterm labor). When I was experiencing my SCH, I had read about this, but did not really believe it would happen to me (of course ;). Currently, I am thinking my past SCH is one increased risk factor of several for my current cervical issues (another being the fact that I have a multiple gestation). Ah, the fun! lol
BTW, I am still working several hours per day from home, but always while lying on my side as instructed. Which is doable, but not exactly ergonomic, lol. My staff have been quite good about it all, and people at the office in general have continued to contact me as usual, which is what I had asked them to do. So that has been going pretty well. I have some more things to finish up remotely before I truly go on leave. I imagine this will take a few more weeks.
Last but not least, I'd like to give a shoutout to my DH, who has been doing virtually all of our homecare and childcare duties while I've been on bedrest. He's been a real trooper about it, and is very supportive of us doing whatever it takes to keep these babies growing safely inside. So Glossup - thank you! xox 
(Our DS has been really understanding and even helpful too! He's 4 so can generally understand what is going on.)