The claims are very similar to the court cases. It is very important to show the good intention. Accordingly, if you have am RFI that you know it would impact the project completion date if delayed; you need to notify the Engineer at early stage that this RFI is important and we are expecting your reply on or before XXX date. 2-3 days before the deadline you can send a reminder that this RFI yet to be answered and it has an impact to the project completion date if delayed so please reply on or before XXX date. If the Engineer did not reply you keep sending a delay notice update every one or 2 weeks until you receive the reply then you can submit your case accordingly.
There is no standards in this subject, i am sharing with you my experience.