from my experience. Texting her within the next couple hours after number closing is usually pretty successful. But I dont usually ask her out then quite yet cause then i seem impatient or clingy. I would usually say something funny to make her laugh and remind her of when we met. Like "Hey Bonnie, i was thinking about robbing a bank but just needed a partner."
her- "lol what...?"
me- "i just needed someone to help me the next time i decided to rob a bank "
her- "haha ok well im up for the job "
then i text her like two days later with a similar thing and then met up for drinks and ended up farking afterwards. so usually text her to remind her of meeting me and then text another day to setup a meet