After 31st August or with Football League permission before that. I have altered the swearing as the filter is obviously still not working, just in case a Mod sees it
However, the embargo is only in place under Regulation 19, which means that when the issue causing it has been resolved the embargo is lifted. The reason there's an issue is a loan where the people lending them the money were told they'd be repaid when Watford received installments of a transfer fee or they could take it from their FL/PL payments. The bold bit they did without the permission of the FL. Repay the loan early and there's no issue. Also, if Watford cease to be a Football League club (by getting promoted), how is the football league able to block their transfers? It'll only be a matter for the PL and the FA.
I thought the penalty was imposed by the FA rather than the Football League? Not that it matters, it seems there isn't really a penalty at all.