You are doing it wrong.
There is an option in the Hive settings to either:
1 - have the heating start at the specified time
or
2 - have the temperature reached by the time you specify.
The system "learns" how long it takes your house to heat and will start accordingly if you choose option 2...
I have a Hive thermostat (2 actually as I have dual zone heating) plus a number of bulbs and sockets which control my lights etc. and 3 outdoor cameras.
I have a few lamps dotted around my downstairs and they are grouped together and all come on at dusk and go off at a time just after I am in...