Ideally, make your sangria ahead of time so the flavors can meld. A couple of hours to overnight is ideal.
PRO-Tip: Don't add fragile fruit like berries until right before serving as the acidic nature of the lemonade will cause them to deteriorate more quickly. You'll want them fresh and pristine. Do not add the soda until an hour or so before serving so the carbonation does not fizzle out.