23:01
- start with 3 level2 generators, the 3rd one will cost 60 for an income of 2 which is a pretty good ratio
- and add leeches. the first will cost 100 for an income of 4 or 6 depending when you place it, you can see that it can be worth it to add it after your 2nd generator
- later on you'll want diagonal leeches around a generator surrounded by catalysts so you can abandon your original generators and start anew elsewhere on the grid when you reach 1000 
I like using this layout on the way to leader, then removing the top generator once I get taskmasters for the bottom one. More than 4 taskmasters is too expensive anyway, and you need the space for leeches and leaders.