There are cheap ways to take the edge off of noise transfer in old buildings, for example a small platform that effectively isolates the vibration from the floor it stands on (@Point5r yes that’s the biggest problem with noise transfer – not walls or ceilings as you might expect), and deadeners that look like cool wall hangings but are actually sound barriers. I used to design proper soundproofing systems for clubs etc, if you email me the dimensions of your room and where the doors/windows are etc I’d be more than happy to write a list of some cheap and easy (and non permanent!) ways to soundproof that are more specific to your building.
Advice to play during the day is good advice and should be strictly adhered to, but sundays are often a family day so I personally would try to avoid them.
Failing that, in the uk you can hire out rehearsal rooms in a purpose built space for about £10 an hour. These usually include microphones and guitar amps too, so it’s handy if you don’t want to lug heavy gear around. Try googling local rehearsal rooms and get some quotes. They are also good for when you need more space for the band rehearsals.