When to test??

When would you test if you think your period is late but cycles are irregular? I guess they aren't super irregular, as they have ranged from 24-34 days within the past year (I believe 21-35 days is considered "regular"). Prior to trying to become pregnant, my cycles seemed much more regular (27-30 days on average) but now they seem to vary more. I just had a MMC in December so I don't want to get my hopes up but I'm on CD 40 and no period. Worth testing at this point?