Gains usually start around week three for Diabolix. Increased vascularity and muscle fullness will start to happen in the second week. The sweet spot for Diabolix is 75mg but 60 is nice and comfortable and gains can be made there. If running the compound solo and if the user is experienced, 90mg can be done but the sides are definitely more noticeable at this point. It really does depend on the user though and what his body can handle.
For a solo 2 two bottle run, I would suggest a 6 weeker @ 45/60/60/60/75/75. This would leave you with 5 caps left over so you could run 1 additional day @ 75. You might also consider stacking it with non-methyls like 1/4 Andro or EpiAndro/4Andro. I would definitely be cautious about stacking it with another harsh methyl or one known to cause BP issues. I stacked Diabolix with Halo and I definitely had BP issues. I would not recommend stacking the two unless you have some serious BP support, as well as additional NAC and TUDCA (on top of your cycle support supplement).
I went as high as 90mg Diabolix and 100mg Halo and it was too much and unnecessary.