Use the Red as your primary card for the first three months you have it and, assuming you meet whatever other criteria Barclays has for the Silver card (FICO, minimum credit line, etc.) you should automatically see an offer to upgrade. I got the offer to upgrade before the three months were done, but it did not convert until my third billing cycle for the Red had closed. All activity for various bonuses carried over from Red to Silver, which for me was relatively little for the EQM and EQD measures as I converted in January.