For those who intend to stop - however briefly - and engage 1st gear, why do you need to wait for the car to completely halt before changing the gear? Not only is it hesitant and wastes valuable seconds where you may be presented with an opportunity to proceed, but you'll find that 1st gear can be difficult to engage when all moving parts are stopped. In addition, a lot of junctions have a slight gradient so if you completely stop and aren't already in the right gear, you can't catch the biting point at the right time and will have to waste more time yanking the handbrake and missing gaps, or worse, rolling backwards.
When the car has reached a very slow rolling speed, engage the gear whilst looking sideways at the traffic (not at the gearstick). This will give you confidence to release the footbrake and hit the gas if you see it's safe to go. There is no need to completely come to a halt unless you're at a solid stop line placed in conjunction with an octagonal STOP sign. Of course, if it's busy and you're forced to stop for a while, then by all means use the handbrake to stabilise the car while you find the bite point ready to go. Always be ready before your gap arrives.
Practise this skill and become smooth at it before you attempt a driving test. A good place to practise is at roundabouts and mini-roundabouts as the view is usually better there. The technique will work with most 'give way' junctions.