Therefore, I believe delaying investing in Bitcoin until we have discretionary funds is a bad idea. Time is ticking and can't be undone.
Don't you think you are getting it wrong here? That we should invest in bitcoin even when we have not figured out if we have a discretionary income to invest so i believe it's still ok to wait if there is no discretionary income to get started with.
The reason you should invest with your discretionary income is that things might not go as have plan it might go dip so if you invest with discretionary and such thing happens to occur you won't get your self up set because you invested with what you are afford to loss .
I believe this is two dimensional stuff in the sense that if one can be able to start investing in Bitcoin without discretionary for a start and can be able to handle any situation that will come then i think it is fine but if you can not then it will be a terrible and a remarkable mistake for that investor and in this case it will be better not investing at all. it is very much advisable to always use our discretionary Income to invest so that you know and you will be aware you are not touching money meant for other things and there is no point hasitating about this Investment.