It will depend on what orientation you decking boards are laid. Are they running parallel to this doorway or perpendicular to it? If they are running parallel to it then you might want to start your first board there and offset it and have it hanging 10 mm off the side of the ledger board/bearer to close the gap. If they are running perpendicular you could do the same and have the boards slightly overhanging and butted up closer to the door sill.
Bear in mind that you need some type of gap here to allow airflow and prevent moisture buildup inducing timber decay.
I'd encourage you to start your own discussion about your deck that way we can delve further into your questions in more detail.
Please let me know if you needed further information or had any questions.
You could use Zenith 14G x 50mm Galvanised Bugle Head Batten Timber Screws or for an extended lifespan Zenith 14 - 10 x 50mm Stainless Steel Bugle Head Batten Timber Screws. You can also bolt the joists to the bracket, but this could be a time-consuming process depending on how many you are doing. If you were to go the bolt route, I'd highly recommend you purchase an attachment for your drill that will allow you to fit sockets to it. You can then drive all the nuts onto the bolts with a drill.
Please let me know if you have any questions.