The longer a person is involved in a friends with benefits or fwb relationship, the higher the chances that feelings will develop.
You need to be sure that you aren’t talking to a woman who has been in an fwb relationship for a long time and is still trying to resolve whatever feelings she developed for the person.
You don’t have to wait long, as long as you have been consistently spending quality time with this person and you have both gotten to know each other well in that time.
You could stop using dating apps entirely when you have had a conversation with this other person about how you feel about them and about how they feel about you.
It is important that you don’t allow yourself to be too presumptuous about your relationship with this person.