Get your international flights sorted asap. Which means know which airlines fly where, how much they cost and what their terms and conditions are. Then assume everything will change and things could get costly. But - some airlines are doing deals eg Qatar Airlines are currently offering a "change dates as many times as you want for whatever reason" deal. And if you do have to change, how much is the change fee? It might be worth it if the original deal is good. Prediction in the UK is that people are already booking holidays abroad, divers will be determined to get going, so do your homework now. Hotels - book on a free cancellation basis. LOBs - with caution, consider what could you lose. Perhaps hold off and get on their mailing lists for notification of deals etc. And if you don't get on that LOB, what land-based options are there?
I just got a straightforward immediate full refund for a major multi-hopper to see rellies in Australia and on into Indonesia. In the UK you are in a much stronger position if you have a package deal - so I put in a couple of days in one hotel to make the flights a package. Do the maths. Get all your research in place. Question. Would you rather have something reasonably good booked, or would you prefer to wait and see what happens? Prediction - by the time you get there, anywhere worth going to dive will be booked up.
A friend who has been in the travel industry for years advised me to get flights into the major hubs, like Singapore, Tokyo etc booked first. Because if you don't you won't be going anywhere. After that you can work out if you turn right, left or go straight on from there. And she's absolutely right.
And yes, I've got my flights booked into Jakarta already. Very good price. Took best-guess on dates and I will change (subject to availability) if I need to. An extra amount for changes is budgeted in.
I hate smug posts!