if you're playing on mobile don't delete your game, just download and install the new version and it'll update and retain your saves. If you're playing on anything else you should be able to just transfer your save files/folder over to the new version.
V.03 - School Days - was the end of Act 1 in my mind. All the major characters were introduced at that point and Leslie had taken that first step in their relationship. We're in Act 2 now but this is gonna be the longest stage by far as we have so many girls to get through. Act 3 will begin around that 28-30 girls bred section (we're at like, 6 or 7 girls completed right now?) and will take a few updates to get through. All that to say we're like, maybe 20-25% through?