Sometimes gates are announced late and it can happen with short haul that you go from no gate being shown to a B or a C gate being shown together with an instruction to "Board Now"- the idea behind it is that it will take a while to get to the satellite so they want to encourage people to the satellite, even if boarding has not in fact commenced (which it often will not have done). Once on the B or C pier people will often rush from the transit to the gate and then look rather confused when everyone is still milling about because boarding has not in fact started.

Last week I was summoned by the electronic board to "Board Now" from a B gate at around 17:30 for an 18:15 departure- fair enough as the boarding time would usually be 17:45 and you would need around 10-15mins to get to the B gates. Having arrived at the B gate at around 17:40, boarding did not commence for another 40 minutes (!) as the crew had not arrived yet. Pretty annoying to say the least.