Do you think I'd be better off going up one size in my suit jacket before getting it altered?

Hey guys, firstly apologies for the creasing, I ordered this suit off the rack and their return instructions are clear that they will not accept returns/exchanges that have been ironed. Obviously intending to have this suit altered however I'm aware that shoulders are often the hardest part to change, do you think this size suits or should I look to go up a size? I believe the pants fit fine/will just require hemming but welcome to advice there as well. Thanks in advance!