Hey @Reuben,
There's a few issues here. First, it appears you're using DateTime.Now to set your sampledToday variable.
DateTime.Now will give you the system's current time in that time zone. You should instead be using the Time property of QCAlgorithm:
sampledToday = Time;
Also, it appears you're comparing your timespan again with DateTime.Now instead of the algorithm's Time property.
The last thing I modified was setting your custom data to use fill forward behavior. This will copy the daily data onto the minute bars. I've also defined the exchange property so it doesn't perform fill forward over weekends and during not equity trading hours.
I've modified and attached the algorithm. Let me know if you have further questions on algorithm Time.