Congratulations, Jas!!
I'm so glad the surgery went so well and that you didn't need the hemmie-ectomy.
The packing is uncomfortable, but it should come out with the first or second bowel movement. I didn't have significant packing, so perhaps others here who did can give you good advice on that.
I took Miralax the evening of the day of my surgery, around 9:30pm - I was already taking 1/2 doses twice a day before the surgery and I just pretty much kept to my schedule after the surgery, but I used a little bit more because of the pain killers (i.e., about 2/3 dose twice a day, around 9am and around 9pm in the evening).
The first week is the most difficult part of recovery, but you'll be just fine. Don't be afraid of the first BM. It's scary but it doesn't hurt very much (certainly not as bad as the fissure pain!). Remeber to take deep yoga breaths - don't push - and relax and the BM will be ok.
Take it very easy this evening, take your pain meds, and take the miralax - as Dawn says, even taking it now would be good.
Good for you, Jas! You're now on your way to healing! :D