Ok so Bella has never had a toilet accident before... when I got home last night I took off my shoes and no less then 2 minutes later Bella had peed all over my shoes and a little mark on the carpet.... she is 6 months old on 5th of August so i am wondering if this unusual act is because she may be coming on call. I am not sure what signs to look for...
Get her spayed ASAP, and then no need to worry about the signs!
Have you noticed anything different about her behaviour too? Hopefully it's just a one-off occasion. She may be making her mark or it might be an unrelated behavioural thing... I'm not sure tho

They can spray when they come in heat, and if she's not spayed, I'd get it done as soon as possible before she's spraying all over your house.
If she hasn't been spayed it is quite normal for girls to spray or pee on things especially shoes coming in with outdoor scents on them. You really do need to get her spayed, not just because of the spraying and peeing but because calling and not being mated can lead to serious health problems in girls.
We have planned with our vet to have her spayed in mid August as that was the earliest we could do it...In regards to behaviours she is constantly trying to run out the back door but other than that there isn't anything else i have noticed which is different
Glad to hear you have the spay setup. Just keep a good eye on her. We have had girls come into heat at this age and waiting until mid Aug. should be no big deal.
She shouldn't come to any harm in the next few weeks, unless she gets out of the back door!! I just hope your shoes last that long

Yikes! It probably is a sign of her coming into season. Good thing her spay appt is scheduled! I am sure her little hormones will settle when it is all done and over with

For now I would just be extra careful with leaving things that have been outside in her reach, as well as making sure there are minimal other triggers to get her to want to spray more. Hang in there!
I think it's unusual you haven't noticed any other changes, from what people say it's pretty obvious. Hope she gets on well getting spayed in a few weeks and like Jane says your shoes don't suffer to badly!!