It's good that you are taking a week off to start the MC I usually advice at least taking the 1st 3 days off since those are the toughest. Most folks go about their regular daily lives on the MC. When I'm out and about I always carry some lemonade in a collapsable cooler with some of those reusable blue ice packs. Also make sure that you stay well hydrated in the summer heat by drinking water in addition to the lemonade.
You plan to give yourself a few hours before work is sound as the SWF generally takes 2 hrs +/- to go through you
The best adevice is to read the FAQs at the top of the page and browse the forum. You'll find a wealth of info. Also there is a search function at the top right of the page to reserarch any particular questions you may have on the MC
Under optimal conditions the MC should not be done if you are not having at least one unassisted poop per day pre MC. If that is the case for you then you should consider looking into colon cleansing first. Have you considered colonics? or maybe one of the easier to do oxygen based protocols like Oxypowder?. Once you are having one unassisted poop each day then you can do the MC to clinch the deal.
What you really need to consider is that barring any congenital or actual damage from years of abuse that your current lifestyle/diet is causing this constipation. The cleanses will help you take the trash out but that is only a temporary solution. You are doing a really good thing and pointing yourself in the right direction with the green juices and fruit but obviously that is not enough. After you do some colon cleansing fasting etc you need to consider what else you are putting into your system that may be causing this constipation and do some research to find something you resonate with and look into some overall dietary changes
I would recommend you look into the oxygen based colon cleansers like Oxypowder. They are mainly composed of magensium and when it mixes wiht the gastric juices it releases oxygen which in turn causes rapid oxydation that melts plaque and impacted fecal matter. If is fairly easy to do also and generally you only do it for one week.
Oxy just happens to be the one I'm familiar with. I had heard of Colosan before. Just didn't have any personal experience with it