Getting tested together before becoming sexually active with a new partner is a thoughtful, increasingly common step. A standard screen usually includes chlamydia and gonorrhoea (urine or swab) and HIV and syphilis (blood). Depending on your history and risk factors, a clinician may add hepatitis B and C, trichomoniasis, or discuss herpes testing.
Timing matters because of window periods: if either of you has had a recent exposure, some infections may not yet be detectable, and repeat testing may be advised. Being open about recent partners, symptoms and any past STIs helps the clinician choose the right tests and sites (including throat or rectal swabs where relevant).
Many regions offer free or low-cost confidential testing, including self-sampling kits. A licensed doctor or sexual-health service can recommend the exact panel for your situation and explain when results can be relied upon, so you both start the relationship with accurate, up-to-date information.