Most agents pay up very quickly as the payments come out of the outgoing tenants deposits.
But more and more tenants are missing the last months rent and then doing a runner,so effectively they are using up their deposits,so the agents use this as an excuse not to pay you.
They will delay paying you until the property has been relet,this can be weeks or even months,luckily only a minority of agents work this way,so when you get your money either get an assurance that you will be paid promptly in future or don't do any more work for them.
LA work can be very rewarding and very often the houses are unfurnished so that makes it an easy clean.
Downside is the carpets are often minging,but it's nice to see the finished product after you have cleaned them.-John