You can lengthen the timeout using the lsp-response-timeout option: https://emacs-lsp.github.io/lsp-mode/page/settings/mode/#lsp-response-timeout
Of course, what you really want to do is make gopls faster. Probably not much you can configure in Emacs to do that.
As mentioned in the comments, a workaround for this issue is to start emacs on a folder (or on nothing) instead of on a single source file.
This was discussed for VScode with gopls as backend here: https://stackoverflow.com/a/49977881/497180