Pour buckets of water down the toilet until you see it in the tube. This may give it enough statistic pressure to clear your clog. Be patient, the water pressure may take 5-10 minutes. If not, your could try a manual snake from the discharge (only as a last resort). I find it better to fill if not all ready full prior to dumping in all cases.
Don & Dona W/yorkies Gizmo, Master Chief, & Tali
2011 Flagstaff 8528 BHSS 2015 Ford 6.7 XLT
2010 Full Timers & Still Going