Ultrasound

I have fallen pregnant after a missed miscarriage in November I got 3 positive pregnancy tests 7 days before my period was due.. My doctor has taken bloods and has told me I should organise a ultrasound for 10days time that will make me roughly 7 weeks pregnant. My question is will any show at 7 weeks? Or am I better off waiting another week until I am 8 weeks pregnant the wait is killing me already