mgmat CAT has a more forgiving scoring system. Their previous tests (not adaptive) were notoriously difficult, but not impossible like the Kraplan ones.
I wouldn't be too encouraged about your score since it was un-timed. Honestly, from this point on, you should time everything. One of the skills that the gmat tests is time management.
Other than that, it's a great start. As for the GMATPrep, if you've read my posts, you'll know that I think it's golden. However, don't wait until the last week to take it. That would be too late in the game. I took my first GMATPrep after I confidently learned almost all of the concepts that was tested. After that, I took the second one about 2 weeks before the actual test, the night before the deadline to reschedule. I told myself I had to break 700 on GMATPrep2, otherwise I would have to delay the actual test. That was great motivation.
Good luck