Although you do of course run the risk of missing out if you're not available to get on straight away to purchase in the next sale, or the website goes tits up, or the opposition in the second group game takes a bigger allocation than the first game, or UEFA and the corporates decide they want far more tickets for the second one because it's a much more attractive fixture.
Up to you, but I wouldn't be messing about and taking that risk personally. Be happy with getting the credits, and knowing you will be in the first sale next time we're in Europe.