Waitress- When to tell work?!

So, long story short, I left my corporate job after I enjoyed my generous maternity leave with my first (born September 20, 2018) so I could stay home with her. Turns out I’m very restless and a workaholic and I just had to pick up a little tiny job 2 nights a week.

I’m serving and I’m super worried about the heavy lifting I do in my (mostly closing) shifts. I never had to worry about this the first time around as I had a desk job. I typically lift glass racks up to ten times a shift, carry ice buckets back and forth and lift them to dump them about 5 times, and carry a bus tub full of super heavy dishes at least ten times. They’re all easily over 20 lbs.

I JUST found out yesterday that I’m expecting, I don’t even officially miss my period for another two days and I don’t get my blood work until Friday but, I got many very clear lines. I’m VERY private; my first pregnancy and I didn’t tell anyone other than my husband for 16 weeks. How do I go about this? Do I tell my manager and hope that he keeps it quiet? Do I just accept that people will know sooner than I’m comfortable with in exchange for keeping my growing nugget safe? It’s really ironic because I just joked with my manager last week that when I get pregnant (we were trying for our second for quite a bit) he has to put me on the host stand to which he replied “or you can just assistant manage?” So I think he would be understanding. It just freaks me out to tell anyone so early. But, the alternative is some serious heavy lifting and bending. Is it dangerous at 4 weeks?