Made an octoberfest tonight, forgot to get gravity before I added yeast. Will it make a difference? OG is 1.05. There is a lot of malt, so I'm not surprised.
if you mean checking OG within an hour or two of pitching...yer fine and the test is accurate.
but after 24 hours your yeast should be churning, and would have consumed some of the sugar, lowering the OG from the actual starting value.