OK I checked the page the image is taken from and it looks like you will be really titrating with iodate - that's strange if you ask me, as one of the prerequisites of reaction used for titration is it its perfectly known stoichiometry,and I am not convinced adding iodate to the solution already containing a reducing agent other than I
- is a good idea, as side reactions can make the method irreproducible. Classic approach would be to add well known amount of iodate to excess iodides, then to add ascorbic acid, then to titrate excess iodine with thiosulfate, apparently you are expected to take a shortcut.
I have no choice but to believe it was tried and gives good results.