No, it would be best if you didn’t consider Grey Market Premium before applying for an IPO as you never know how reliable the source of information is and how to try it might be. Moreover, the information is tentative to change very quickly.
Whatever information you receive through a grey market about investing in an IPO should be taken with a pinch of salt. You could consider the information as part of your investing strategy but remember that any information here is tentative to change quickly and doesn’t guarantee you any long-term gains whatsoever. From the time you receive the information to the time you invest in the IPO, gray market information changes in a heartbeat.
However, you could consider going the authentic route of analyzing a company based on its financial performance for the past five years, the issue size of the IPO, business model, future plans, investment ideologies, and so on. Never get fooled by considering anything from a Grey Market. Some things might be true, while others are changing on the go.