Sorry Longers....one may well be me...but as you said pay "by", then I timed my payments accordingly...honestly (see calendar reminder below)...
...However, money paid (full amount now)...appreciate the organisation and commitment from you for us to have a good time; the least we can do is pay up...
Yes I did say "by" but if I leave it until Sunday to remind people (based on experience so far) I'll be chasing them this time next week. Trouble is that by this time next week I'll need to have sent several thousand €s to some hotels to confirm our reservations...