EPG data is not preserved when the Toppy is turned off, so it starts with no data when it first comes out of standby. However, it does not take long to collect a lot of data, especially when tuned to the better BBC channels. You should also be able to see the EPG Guide being populated with new data while you are looking at it.
As the number of Freeview channels increased beyond what was envisaged when the Toppy firmware was written, from about May 2012 the EPG has ever more gaps, as it simply doesn't have enough slots for all the programmes. Deleting unwanted channels doesn't help; the whole lot are stored. It's unlikely there'll be new firmware. Workarounds: to see more for a specific channel, tune to it, then go into standby and restart. More entries for that channel will probably get filled, at the expense of other channels. If not all multiplexes are required, tuning to only 4 or 5 of the 6 will probably reduce the number enough to eliminate the gaps, but this is likely to be unacceptable. Or use a TAP that stores its EPG on disc, such as MyStuff or Jag's EPG. See for example this page (for Humax and Topfield), message #3.