300-450mg is what you take to 'hallucinate' all though it's not hallucinating, it's delirium. As close as fear as you can get in tablet form. Some users report it taking a long time to see anythings, some sooner. You just need to fight the feeling for sleep, no point taking more and more thinking it will make it come sooner or anything like that.
Just take 300-450mg and then relax, watch a few films, listen to music, go for a walk (yeah it's hard but I find walking on a DPH trip to be amazing, especially in the dark with street lights on), try talk to friends. You'll notice at first black dots moving at the side of your vision, then they usually turn to spiders, bugs, or birds, then they start appearing in the centre of vision. So life like, they walk up you and you swear you can feel them, you think you're talking to people to then realise you aren't talking to no one but then you forget what happened and you don't even know what's going on and you're talking to someone but then you remember what happened and you aren't actually talking to anyone. Then shit starts to get real. At least that's how my DPH trips happened from what I remember.
EDIT-
Just found this channel on youtube and came across this video on it. It'll answer pretty much everything you need to know about DPH. -
https://www.youtube.com/watch?v=N-H79YsNK-0
If a mod sees this can you speak to the website admin/boss about adding this channel to the forum for easy access. It's full of tonnes of informative videos which many users here would greatly benefit from. You'd also be helping a youtuber out.