6.1) Give applicants a reply ASAP - if it's a NO they may still want to buy a paid ticket during the early bird pricing window
6.2) Give applicants a reply ASAP - if it's a YES they will also need to book travel and accommodation - making them wait exposes them to higher costs
7) Consider allocating tickets on a first-come, first-served basis, rather than judging applicants against one another
8) If your quota is exceeded consider offering discounts to the other applicants
9) Make it clear that their presence at the conference is enough for you. There is no quid pro quo required in the form of having to attend diversity photoshoots etc
10) Consider how the event will look to diverse applicants when they arrive - what's the culture you are representing and is it narrow or broad (e.g. do you have a COC, diverse speakers, quiet room)