This seems like a fairly normal timescale for a deal of this size, to be honest.
IAG has offered concessions - slot handbacks etc. The Commission will now be "market testing" them, i.e. going out talking to other affected airlines and other parties, and asking them "does this seem reasonable and will it overcome the reduction in competition?" In some cases they'll be asking "Is the proposed package of concessions enough to get you to consider entering one or more of these routes?" The IAG concessions were only sent to the Commission on Friday so will only be going out from the Commission in the next couple of days, I'd imagine, and it's reasonable to give the market-test participants a week or two to assess them, especially since at least one or two of those participants are likely to have a bank holiday weekend coming up...
