It depends on the rescue - if they're small, independently run rescues like ours, it usually means someone is doing it and juggling full time work / families - so not always instant! I always reply to emails / phone calls daily, but depending on work / home schedule it could take a week or two to arrange a convenient time for both parties for the homecheck.
Each rescue is different with their criteria for rehoming - some won't rehome if you have no grass, e.g a flat for example - others will, as long as you can provide an adequate diet for them without grass. I've rehomed piggies to homes without grass before, it depends on the situation.
Sophie
x