If memory serves, the half life of Buprenorphine is around 36 hours or so. I think the naloxone in there has a HL of 1-2ish hours? For me I could usually break through after the 10-12hrs, with a diminished high. 24 to 36 before the full effect was nearly back. This is referring mostly to Heroin and Fentanyl usage, with other things ymmv.
Assuming you were accurate in your guestimate of half of the pills being dissolved (there is much more surface area on the outside of a pill, so LOOKING like half is likely more than half), in 36 hours the naloxone is nearly gone, but you'd still have 4mg Buprenorphine in your system. Even though buprenorphine is an opioid, it is an antagonist to most opioid receptors, and only a partial agonist for others; This, combined with the fact that it binds strongly to the receptors it effects means it's not just the naloxone blocking you from getting high. This hasn't even factored in your weight. The less you weigh, the more milligrams per kilogram your body has to deal with. If you weight less, it could take longer to totally wear off. I'm a bigger guy, and rarely took 8mg at once, so my numbers above may not be the same as yours.
Finally, take this post with a grain of salt. I'm not a doctor, biochemist, pharmacist, etc. This is not intended as medical advice of any kind, just information. Everything I've said is based of things I've read and my own personal experience. Make sure you double check the things I've said... After all, it's coming from my memory, which is at best maybe above average, but nowhere near perfect. Good luck and be safe!