He called me to the restaurant and said, “I’ll think about it.” How to react? ⇐ Pick Up

[Anonymous]

Hello everyone.
I ask for advice from experts in female psychology and practicing pick-up artists.
About me
38 years. Slender build. Lead engineer at an oil and gas corporation.
About her
28 years. Fitonyashka. There is no other information.
Situation
I met her while Tinder was still alive, we corresponded for a while, then we got lost for 1.5 years. A year ago I met her in the gym (we go there to train), I recognized her, and she recognized me too. After a year of going to the gym together (we didn’t communicate there at all, we just looked at each other), I wrote to her on Instagram with an offer to have dinner at a restaurant, she said that she would think about it.
Question
Should I wait a couple of days and ask about her decision or should “I’ll think about it” be interpreted as “I’m not interested in you, back off”?