A first for bath time...

Ruth Ann has been sitting up unsupported for about 2 months now...but I haven't really trusted her sitting up on her own in the tub. But over the weekend I was brave and left our bath sling at home so I was forced to bath her without it while we were at the beach...and like I had hoped she was perfectly fine. The only sad thing is she looks like such a big girl sitting up in the tub playing. I want her to stay this cute and tiny forever...how can I go about freezing her at 8 months old??