The 8 days for a speed 2 was a bit much for me, i think 5-6 is just about perfect for a speed 2. The reason i think 5-6 is enough is that coming out of BP with conquest research done and an army to support it yourself seems a bit crazy to me, there should be a decision that the player has to make as regards rushing for conquest but missing out on the initial BP or building up his army at the expense of slower expansion.
If this was a revolt speed 2 world with this BP i probably would have given it a miss to be honest, long bp results in horrific morale punishment
In my opinion 4-5 is about right for speed 3, again i think you could go longer with no morale but no more than 6 would be necessary. That being said speed 3's are crazy fun so id probably play anyway