I've been leafleting 4.5k per month for the last 2 months and I am genuinely astounded at how much new work is coming in.
Also about 50% of the enquiries are good!
I shall continue leafleting every month, even December, mainly because the guy who delivers my leaflets is excellent, good value and I want to help keep him employed, ready for the New Year.
is the success rate about 1 / 2 % ? ( on a blanket leaflet drop )
I have a good success rate when I hand deliver myself... but then I target certain types and avoid the types I dont like.
I also put a price on the back of the postcard for their property......(adding x amount extra if they have a conservatory}
I also put a first clean price down.
the thing is though that its a ball ache doing it myself after grafting all day.
I am thinking of paying someone to do a blanket drop next spring.
my other worry is that I dont like doing more than 5 first cleans a week.
its great that its working for you 
It really depends on the area
First 1,000 got me about 20 enquiries, I just hit lucky!
The lowest 1,000 has been 1 enquiry
Average 1,000 is about 6-10 enquiries
But to be honest i've lost count as the phone rings, pretty much, every day.
I also have a good website and good Google ranking, so I do get calls off of those as well and that is additional to the above.
The downside is that windies are using Covid as a way of dumping customers, so you have to be careful not to pick up their crap!
I keep my costs low, I designed my own leaflet and my printing costs are about £30 for 5,000, delivered.
The trick of all of this, is getting the leaflets delivered and not put in the bin, I just hit lucky with my guy.
As for first cleans, save them up and do them on a Saturday.
Mrs Window Cleaner loves to go food shopping on a Saturday...make a list, then to Aldi, then to Sainsburys for all the other bits, then to the butchers for the meat (she likes a good bit of meat!). Clothes washing, bed washing (I've woken up before with no bloody covers over me, where she's stripped the bed)!!
It's a manic environment....so I work...I relax...I do my thing.
I love first cleans, you need 2 things:
1. A magic eraser pad, attached to a gardiners quick loq with a single strong elastic band. Don't make it look pretty or uniform, you need the odd bits sticking out to get into the grooves and crevices of the windows, great for getting black stains off.
2. Pink stuff, in a tub. Take the lid off, push the tub onto your brush and swivel it clockwise and anti clockwise, until your bristles are....pink. Cleans everything! And rinses well too.
You only like doing 5 first cleans a week...good luck with that, you should be doing loads!