Protecting your own emotional and physical boundaries is the foundation of safe connections. It often happens that a new acquaintance starts to force events: confessing their feelings too early, demanding a meeting, or constant 24/7 contact. Such pressure can be a sign of controlling tendencies.
You have every right to independently determine the pace of getting closer. If you are uncomfortable giving out your phone number after one day of texting, say so directly. A healthy and adequate person will accept your caution with understanding and will not pressure you. If, however, you receive aggression or insults in response, it is a clear signal to immediately stop communicating.
Establishing boundaries also applies to topics of conversation. You are not obligated to discuss your past relationships, financial status, or deeply personal experiences with someone you barely know. Listen to your inner voice: if a conversation causes discomfort, feel free to change the subject.