I will say we desperately need an r/cricket alike before the Ashes starts. Was rather hoping not to have to take matters into my own hands - but if I understand your intention, your sub is more about playing, right?
Edit: just found c/cricket on lemmy.ml and lemmy.world, but maybe a UK-oriented one wouldn't be a terrible idea...?
I think the best way to promote is to announce, but not to make any assumptions about whether yours, or a competing sub of the same topic, is the one that is to take off with popularity.
I think subs of similar topics should merge until communities get large enough to desire a topical split.
Right now I'm looking for similar communities and making posts redirecting them to mine. You could probably promote outside of Lemmy but then you have to explain how everything works which is not my strong suit.