From the Boom Beach forum:
Here’s a quick update on where we’re at with the Android version of Boom:
Firstly, it’s looking like June will be the month where we start gradually rolling it out!! Please bear in mind that this isn’t set in stone, but it is the current plan
Secondly, we’re ramping up our player support to be able to accommodate the new players at the moment. This can’t happen over night and we need to do it properly to make sure all of the new players have sufficient support – it’s very important to us that we have the right support in place before we open the Android flood gates!
Thirdly, thank you very much for your patience so far!