There are so many factors in play here, it is hard to answer your question. What are you expecting, what are your goals? Paid or free app? Who signed up for th

There are so many factors in play here, it is hard to answer your question. What are you expecting, what are your goals? Paid or free app? Who signed up for the list. Are they targeted? What % of them do you think will download? Do you have other ways to get people to download your app instead of the waiting list? What are you doing to build a relationship with the list to entice them to download. Is the app any good? Is it exciting? Does it solve a new problem? Do you need a wait list at all? As a quick answer I suggest forget about the wait list and make your app awesome! Then drive people to download the app, not join the list. Build a list once you have the app, to remind people how great/useful it is with helpful articles etc. So they keep using it. P.S. the percentages you mention are meaningless on such small numbers. Forget about % growth until you have a few 1000 in the list.