I am also HGT1 - I don't want to jinx myself but my BCG treatments have been very tolerable.
I was tired the day after my first one but think it was more due to the stress I had leading up to the procedure.
I did not have any physical side effects until my treatment last week. There was stinging as they were prepping the area for instillation but we think it just might be my urethra getting irritated from weekly catheter insertion.
I was so nervous about starting treatments but feel very lucky that side effects have been so few. Two more to go!