timeline chart with offset??

[Gabriel]

Hello,

I am trying to draw a timeline - based chart with electical measures,
that is, a consumption graphic along a week, for example.
We have a measure model with a date attribute, a DateTimeField. Each
time a user registers a an electrical measure, it is added to the
database, registering its value and the date.

What I did, is to convert DateTimeField to string, and then to int,
so, if we have a date 2011-11-01 01:18:27, it becomes to 2.01111010118e
+13.

The problem is, when I do a draw, the bars are so far away from zero,
because I cannot add offset.

Do someone now how could I add offset?

Thanks,
Gabriel