You can do it yourself. However, if you've never done it before, there's quite a lot that you may or may not understand, and it is quite a steep learning curve just to do it all manually - Movie Magic is an even steeper learning curve.
If you have the money to hire a professional, I probably would. You can do it yourself, but there's a lot to budgetting and scheduling and you need to know you're doing it right - even just the difference between scheduling 6 pages and scheduling 5 pages. ADs tend to know (especially if given a shot list) how long a setup may take, so whilst you may be ambitious and just guess that you might get 6 pages shot in one 12-hour day, an AD will look at it and say well you've got a two dolly setups, a location move and an entire night scene to light, let's schedule 4 pages so that we don't end up running behind.
At the end of the day, when you submit your progress report, you want to show your investors that you're at least running on schedule, of not ahead of schedule. You don't want to submit a progress report that shows you scheduled 6 pages, only shot 4 and now need to pickup those two whole pages somewhere else in the schedule, costing more money, possibly bringing cast and crew back for another day etc etc.
Plus you need to have crossplots plotting when people are available vs when they're working and all sorts of things. And, a professional will likely move scenes around to save time and money in ways you may not have thought of before - ie scheduling it so that we finish a scene before lunch so 4 of the 5 cast in that scene can go home which means we only have to pay for catering for 10 rather than for 14, scheduling all the dolly shots after lunch so that we can have a runner go and pick it up and only pay a half-day rate rather than a full day rate, scheduling so that whilst we shoot an intimate scene with skeleton crew, rather than doing it at the end of the day, do it at a time when the crew who aren't needed can go to the next room that we're shooting in and set that up so that as soon as we've finished shooting here, we can move on and almost immediately start shooting etc. etc.
Also, in terms of budget, there are all sorts of legal issues when it comes to things like overtime pay and workers comp and defferred payment contracts etc. so I'd at least be getting a professional on as a Producer to take care of the budget stuff and all the logistics and logistical/legal documentation that you may not necessarily have much idea about.