My GP called me last night to let me know they found traces of blood in my stool sample and she was going to refer me to the specialist and they'd probably do a colonscopy. Does anyone have any idea how long this process usually takes?

Background 

I'm a 30 year old female. First developed pruritus ani in 2019, my GP done a rectal exam didn't feel anything, prescribed me some creams to try which didnt work, so I went back and tried worming tablets again they didnt work but I never ended up going back. Around this time last year I noticed bright red blood when wiping, but put it off as I was going through referral for a laproscopy and felt like I already had so much going on the GP wouldn't take it seriously. I only noticed it probably once after that, then last month I noticed the blood again when I wiped so I thought I'd speak to the GP as the anal itching never fully went away and id noticed sometimes when I was wiping I was also getting mucus and at times it felt like I still needed to go to the toilet even after Id already been like I could feel it in my lower back but couldn't actually go. Ive now also seen that low iron can be a bad sign which ive had for years and the GP just kept prescribing me with iron tablets saying they didnt know what was causing my levels to be low when I asked as I was confused as I eat a balanced and varied diet of foods. 

Has anyone else had any similar symptoms? 

Thankyou in advance