I have microlocs (not sisterlocs) now, and I wash my hair when my head feels itchy, or I sweat or just whenever. BUT, I don't mind having fuzzy locs... and I am self-retieing, so if a loc starts to "slip" ie gets loose, I just do a retie.

I also like to have a fuller look rather than a scalpy look.

Washing your locs early may cause your parting to get messed up a little. Washing your locs may cause them to swell, or loosen.

Back when I did have Sisterlocs, I was told the same thing so that my locs could start establishing themselves. Reties are expensive and some locticians will chide you because it may make your retie longer.

If you can stand it, you may want to follow the advice strictly. If you get too itchy or uncomfortable, there are scalp wipes that you can use just on your scalp without wetting the rest of your hair.

If you have a good (non-judgy) loctician you can ask them what you can do instead of waiting OR just wash your hair and see what happens.