How long should I wait for the receipt acknowledgement?
Most journals work with electronic submission systems but some still work with manual handling. Regardless, both systems require a person to handle the manuscript once it arrives. Since the past week has been the Christmas holiday for many and persons working with journals such as editors are usually not employed to work with the journal but do it aside their regular job, it is not strange that not much will happen during the holiday season.

I am sure you will receive notice of your submission sometime in the next couple of weeks into the new year, once the persons responsible will have a chance to have a look.

As a side note, as an editor, I can see that the number of submissions is slightly increasing before summer (holidays) and Christmas/New Years (holiday season). Authors, naturally, want to get their works away before taking time off, unfortunately, editors and reviewers, naturally reluctant to take on reviews during the holidays, do the same so the increased flux of manuscripts creates something of a traffic jam at these times. From this perspective, submitting a manuscript away from these times of the year will likely result in, at least slightly, faster response and turn-over times.