Very long come up on DXM?

[captaintom]

I took 675mg of DXM almost three hours ago and so far have felt little apart from some mild dissociation and warm body feelings.
By my body weight I calculated that this would bring me to a third plateaux experience. I've smoked cannabis which potentiated the feelings slightly.
I ate earlier in the day but only a very small amount, half a burger and a spoonful of my friend's unwanted mac n cheese at around 2pm.
I took the dxm at 7pm and i don't understand why i'm not feeling more?
Is there any chance i've somehow had an incredibly long come up or is this likely to be an underwhelming experience?

 

[sekio]

What form was the DXM in? If you've been eating the gelatine capsules they may not have all burst.