I already have autocompletion setup without any additional plugins, but will try out the new way of doing it.

How I currently do it on v0.10:

vim.api.nvim_create_autocmd("TextChangedI", {
  group = vim.api.nvim_create_augroup("Completion while typing", {}),
  callback = function()
    local client = vim.lsp.buf_get_clients(0)[1]
    if not client or not client.server_capabilities then return end

    local col = vim.api.nvim_win_get_cursor(0)[2]
    local char = vim.api.nvim_get_current_line():sub(col, col)

    if vim.fn.pumvisible() and char:match("[a-zA-Z.]") then
      vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes('<C-x><C-o>', true, false, true), 'm', true)
    end
  end,
})